As filed with the Securities and Exchange Commission on April 29, 2019

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 20-F

(Mark One)

OR

OR

OR

Date of event requiring this shell company report

For the transition period from            to            

Commission file number 1-14418

SK Telecom Co., Ltd.

(Exact name of Registrant as specified in its charter)

SK Telecom Co., Ltd.

(Translation of Registrant’s name into English)

The Republic of Korea

(Jurisdiction of incorporation or organization)

SK T-Tower

65, Eulji-ro, Jung-gu, Seoul, Korea

(Address of principal executive offices)

Ms. Hye Young Jung

65, Eulji-ro, Jung-gu, Seoul, Korea

Telephone No.: +82-2-6100-2114

Facsimile No.: +82-2-6100-7827

(Name, telephone, email and/or facsimile number and address of company contact person)

Securities registered or to be registered pursuant to Section 12(b) of the Act.

* Not for trading, but only in connection with the registration of the American Depositary Shares.

Securities registered or to be registered pursuant to Section 12(g) of the Act.

None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act.

None

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

71,869,828 shares of common stock, par value ￦500 per share (not including 8,875,883 shares of common stock held by the company as treasury shares).

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes   ☒    No  ☐

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    Yes  ☐    No  ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or an emerging growth company. See definitions of “accelerated filer,” “large accelerated filer” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer  ☒            Accelerated filer  ☐            Non-accelerated filer  ☐            Emerging growth company  ☐

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.    ☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP  ☐     International Financial Reporting Standards as issued by the International Accounting Standards Board  ☒     Other  ☐

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow. Item 17  ☐     Item 18  ☐

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

TABLE OF CONTENTS

(i)

(ii)

CERTAIN DEFINED TERMS AND CONVENTIONS USED IN THIS ANNUAL REPORT

All references to “Korea” contained in this annual report shall mean The Republic of Korea. All references to the “Government” shall mean the government of The Republic of Korea. All references to “we,” “us,” or “our” shall mean SK Telecom Co., Ltd. and, unless the context otherwise requires, its consolidated subsidiaries. References to “SK Telecom” shall mean SK Telecom Co., Ltd., but shall not include its consolidated subsidiaries. All references to “U.S.” shall mean the United States of America.

All references to “MHz” contained in this annual report shall mean megahertz, a unit of frequency denoting one million cycles per second. All references to “GHz” shall mean gigahertz, a unit of frequency denoting one billion cycles per second. All references to “Mbps” shall mean one million bits per second and all references to “Gbps” shall mean one billion bits per second. All references to “GB” shall mean gigabytes, which is one billion bytes. Any discrepancies in any table between totals and the sums of the amounts listed are due to rounding.

All references to “Won,” or “￦” in this annual report are to the currency of Korea and all references to “Dollars”, “U.S. dollar” or “US$” are to the currency of the United States of America.

The Ministry of Science and ICT (the “MSIT”) is charged with regulating information and telecommunications, and the Korea Communications Commission (the “KCC”) is charged with regulating the public interest aspects of and fairness in broadcasting. Subscriber information for the wireless and fixed-line telecommunications industry set forth in this annual report are derived from information published by the MSIT unless expressly stated otherwise.

The consolidated financial statements included in this annual report are prepared in accordance with International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (the “IASB”). As such, we make an explicit and unreserved statement of compliance with IFRS, as issued by the IASB, with respect to our consolidated financial statements as of December 31, 2018 and 2017, and for the years ended December 31, 2018, 2017 and 2016 included in this annual report.

Unless expressly stated otherwise, all financial data included in this annual report are presented on a consolidated basis.

FORWARD-LOOKING STATEMENTS

This report contains “forward-looking statements,” as defined in Section 27A of the U.S. Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the U.S. Securities Exchange Act of 1934, as amended (the “Exchange Act”), that are based on our current expectations, assumptions, estimates and projections about our company and our industry. The forward-looking statements are subject to various risks and uncertainties. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as “anticipate,” “believe,” “considering,” “depends,” “estimate,” “expect,” “intend,” “plan,” “planning,” “planned,” “project” and similar expressions, or that certain events, actions or results “may,” “might,” “should” or “could” occur, be taken or be achieved.

Forward-looking statements in this annual report include, but are not limited to, statements about the following:

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We caution you that reliance on any forward-looking statement involves risks and uncertainties, and that although we believe that the assumptions on which our forward-looking statements are based are reasonable, any of those assumptions could prove to be inaccurate, and, as a result, the forward-looking statements based on those assumptions could be incorrect. Risks and uncertainties associated with our business include, but are not limited to, risks related to changes in the regulatory environment, technology changes, potential litigation and governmental actions, changes in the competitive environment, political changes, foreign exchange currency risks, foreign ownership limitations, credit risks and other risks and uncertainties that are more fully described under the heading “Item 3.D. Risk Factors” and elsewhere in this annual report. In light of these and other uncertainties, you should not conclude that we will necessarily achieve any plans and objectives or projected financial results referred to in any of the forward-looking statements. We do not undertake to release the results of any revisions of these forward-looking statements to reflect future events or circumstances.

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PART I

Not applicable.

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You should read the selected consolidated financial and operating data below in conjunction with the consolidated financial statements and the related notes included elsewhere in this annual report. The selected consolidated financial data set forth below as of and for each of the five years ended December 31, 2018 have been derived from our audited consolidated financial statements and related notes thereto, which have been prepared in accordance with IFRS as issued by the IASB.

In addition to preparing consolidated financial statements in accordance with IFRS as issued by the IASB included in this annual report, we also prepare financial statements in accordance with Korean International Financial Reporting Standards (“K-IFRS”) as adopted by the Korean Accounting Standards Board (the “KASB”), which we are required to file with the Financial Services Commission of Korea (the “FSC”) and the Korea Exchange Inc. (the “Korea Exchange”) under the Financial Investment Services and Capital Markets Act (the “FSCMA”). English translations of such financial statements are furnished to the U.S. Securities and Exchange Commission (the “SEC”) on Form 6-K. K-IFRS requires operating profit, which is calculated as operating revenue less operating expense, to be separately presented on the consolidated statement of income. Operating expense represents expenses incurred in our main operating activities and includes cost of goods sold and selling, general and administrative expenses. The presentation of operating profit in our consolidated statements of income prepared in accordance with IFRS as issued by the IASB included in this annual report differs from the presentation of operating profit in the consolidated statements of income prepared in accordance with K-IFRS for the corresponding periods in certain respects. For additional information, see “Item 5.A. Operating Results — Explanatory Note Regarding Presentation of Certain Financial Information under K-IFRS.”

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Not applicable.

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Risks Relating to Our Business

Competition may reduce our market share and harm our results of operations and financial condition.

We face substantial competition across all our businesses, including our wireless telecommunications business. We expect competition to intensify as a result of the development of new technologies, products and services. We expect that such trends will continue to put downward pressure on the rates we can charge our subscribers.

Historically, there has been considerable consolidation in the telecommunications industry, resulting in the current competitive landscape comprising three mobile and fixed network operators in the Korean market, us, KT Corporation (“KT”) and LG Uplus Corp. (“LG U+”). Each of our competitors has substantial financial, technical, marketing and other resources to respond to our business offerings.

The collective market share of our competitors amounts to approximately 52.8%, in terms of number of wireless subscribers, as of December 31, 2018. We also compete for subscriber activations with MVNOs, including MVNOs that lease our networks. MVNOs generally provide rate plans that are relatively cheaper than similar rate plans of the wireless network providers from which they lease their networks, including us. In addition, other companies may enter the wireless network services market. New entries into such market have historically required obtaining requisite licenses from the MSIT. However, pursuant to an amendment to the Telecommunications Business Act, which will become effective in June 2019, companies meeting certain regulatory criteria may become a network service provider by registering with the MSIT without a separate license requirement, which may have the effect of encouraging new entries into the Korean wireless network services market in the future.

We believe the increase in market share of MVNOs and the entrance of new mobile network operators in the wireless telecommunications market may further increase competition in the telecommunications sector, as well as cause downward price pressure on the fees we charge for our services, which, in turn, may have a material adverse effect on our results of operations, financial position and cash flows.

Our fixed-line telephone service competes with KT and LG U+, as well as other providers of voice over Internet protocol (“VoIP”) services. As of December 31, 2018, our market share of the fixed-line telephone and VoIP service market was 16.0% (including the services provided by SK Broadband Co., Ltd. (“SK Broadband”) and SK Telink Co., Ltd. (“SK Telink”)) in terms of number of subscribers compared to KT with 57.7% and LG U+ with 17.4%. In addition, our broadband Internet access and Internet protocol TV (“IPTV”) services provided through SK Broadband compete with other providers of such services, including KT, LG U+ and cable companies. As of December 31, 2018, our market share of the broadband Internet market was 25.4% in terms of number of

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subscribers compared to KT with 41.0% and LG U+ with 18.9%. As of December 31, 2018, our market share of the pay TV market (which includes IPTV, cable TV and satellite TV) was 14.1% compared to KT with 23.3% and LG U+ with 11.9% and the collective market share of other pay TV providers with 50.7%.

Recently, the Korean fixed-line telecommunications industry has been going through significant consolidation involving major cable television service providers. In January 2019, LG U+ announced its plan to acquire a majority equity stake in CJ Hello Co., Ltd. (“CJ Hello”), which is one of the largest cable television and other fixed-line telecommunication services providers in Korea. In April 2019, SK Broadband entered into an agreement with Tbroad Co., Ltd., a leading cable television and other fixed-line telecommunication services provider in Korea with consolidated total assets of Won 1,192.3 billion and consolidated total revenue of Won 684.1 billion as of and for the year ended December 31, 2018, and two of its subsidiaries, Tbroad Dongdaemun Broadcasting Co., Ltd. and Korea Digital Cable Media Center Co. Ltd., (collectively, “Tbroad”), pursuant to which Tbroad will merge with and into SK Broadband. Upon the completion of such merger, which is expected to occur by early 2020, we expect to own approximately 74.4% of SK Broadband’s total outstanding shares. In addition, SK Telecom signed a separate share purchase agreement with Tbroad Co., Ltd. to acquire a 55.0% equity interest in Tbroad Nowon Broadcasting Co., Ltd. (“Tbroad Nowon”), another subsidiary of Tbroad Co., Ltd., for a purchase price of Won 10.4 billion. While the completion of each of these transactions is currently pending, successful completion of such transactions, as well as further consolidation in the fixed-line telecommunications industry, may result in increased competition, as the entities emerging from such consolidation and other remaining players in the industry may actively pursue expanding or protecting their respective market shares.

Furthermore, the Government has historically enforced regulations on cable TV and IPTV service providers that prohibited them from having a market share of more than one-third of the total number of subscribers in the relevant pay TV market on each of their respective platforms. In June 2015, the Government amended the regulation to impose the same limit on the market share of the entire pay TV market, including satellite TV service providers as well. Such amended regulation, however, expired in June 2018, which has led to the speculation that KT, currently the dominant market player in both the IPTV and satellite TV markets, may further increase its market share by acquiring other players in the pay TV market. While the expiration of such regulation has prompted the submission of a number of bills in the National Assembly to extend its application, it is uncertain whether such bill will be passed. If such regulation is not extended, it may have a material adverse effect on our IPTV business.

Continued competition from other wireless and fixed-line service providers has also resulted in, and may continue to result in, a substantial level of deactivations among our subscribers. Subscriber deactivations, or churn, may significantly harm our business and results of operations. In 2018, the monthly churn rate in our wireless telecommunications business ranged from 1.2% to 1.3%, with an average monthly churn rate of 1.2%, which decreased from 1.5% in 2017. Intensification of competition in the future may cause our churn rates to increase, which in turn may cause us to increase our marketing expenses as a percentage of sales to attract and retain subscribers.

With respect to the e-commerce business operated by Eleven Street Co., Ltd. (“Eleven Street”), 11st, our marketplace business, faces intense competition from various e-commerce providers, including online open marketplaces such as Gmarket, Auction and Interpark and online social commerce operators such as Coupang, Ticket Monster and Wemakeprice. We also face competition from traditional retailers with online and mobile shopping portals such as SSG.com and Lotte.com, home shopping providers with online and mobile shopping portals such as CJ Mall by CJ O Shopping, GS Shop by GS Homeshopping and Hyundai Hmall by Hyundai Homeshopping, and various online marketplaces for specific consumer segments or product groups. The industry in which 11st competes is evolving rapidly and is intensely competitive, and we face a broad array of competitors domestically and increasingly, internationally.

Our ability to compete successfully in all of the businesses in which we operate will depend on our ability to anticipate and respond to various competitive factors affecting the respective industries, including new services that may be introduced, changes in consumer preferences, economic conditions and discount pricing strategies by competitors.

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Inability to successfully implement or adapt our network and technology to meet the continuing technological advancements affecting the wireless telecommunications industry will likely have a material adverse effect on our financial condition, results of operation, cash flows and business.

The telecommunications industry has been characterized by continual improvement and advances in technology, and this trend is expected to continue. We and our competitors have continually implemented technology upgrades from our basic code division multiple access (“CDMA”) network to our wideband code division multiple access (“WCDMA”) network, and subsequently to LTE and 5G technologies. Since first commencing our LTE services in July 2011 and LTE-A services, which use carrier aggregation technology that combines spectrum frequencies to improve data transmission speeds, in June 2013, we have developed and launched various upgraded LTE networks and services providing faster network speeds, enhanced connectivity and broader coverage areas. Additionally, in order to promote the growth of our IoT solutions business, we deployed new networks nationwide, namely our high-speed LTE-M network in March 2016, our low-cost Low-Power Wide-Area network based on LoRa technology (our “LoRa network”) in July 2016, as well as our “LTE Cat.M1” network in April 2018. We believe that these new networks will support the active development and provision of diverse IoT solutions at a lower cost. For a more detailed description of our backbone networks, including our 5G network, see “Item 4.B. Business Overview — Cellular Services — Digital Wireless Network.”

Our business could also be harmed if we fail to implement, or adapt to, future technological advancements in the telecommunications sector in a timely manner, such as the implementation of 5G technology. Following the commencement of the operation of our 5G network on a limited basis for business customers in December 2018 in a few major commercial districts in Seoul and other metropolitan areas, we launched wireless service plans using the 5G network in April 2019 following the commencement of sales of the first 5G-compatible smartphones. We are in the process of expanding our 5G network coverage, beginning with the Seoul metropolitan area and other major cities. KT and LG U+ have also rolled out their respective 5G wireless service plans in April 2019. In addition, we plan to continue upgrading and enhancing our LTE network, which we expect will continue to be used broadly by our subscriber base during the near future, as we and our competitors continue to build up 5G networks and services and wireless service users gradually migrate to the 5G network over time. The more successful operation of an LTE or 5G network or development of improved LTE or 5G technology by a competitor, including better market acceptance of a competitor’s LTE or 5G services, could materially and adversely affect our existing wireless telecommunications businesses as well as the returns on future investments we may make in our LTE network or our other businesses.

In addition to introducing new technologies and offerings, we must phase out outdated and unprofitable technologies and services. For example, as of January 2019, we discontinued our wireless broadband Internet access (“WiBro”) services, and we also plan to phase out CDMA services by the end of 2019. If we are unable to do so on a cost-effective basis, our results of operations could be adversely affected.

Implementation of new wireless technology and enhancement of existing wireless technology have required, and may continue to require, significant capital and other expenditures, which we may not recoup.

We have made, and intend to continue to make, capital investments to develop, launch and enhance our wireless service. In 2018, 2017 and 2016, we spent Won 1,735.6 billion, Won 1,597.0 billion and Won 1,508.0 billion, respectively, in capital expenditures to build and enhance our wireless networks. Our continued implementation of 5G services, which use a higher frequency spectrum than our LTE services, will require additional cell sites and other infrastructure, which may result in an increase in our capital expenditures in the future. We also plan to make further capital investments related to our wireless services in the future, including services that can potentially leverage our 5G network. Our wireless technology-related investment plans are subject to change, and will depend, in part, on market demand for LTE and 5G services, the competitive landscape for provision of such services and the development of competing technologies. There may not be sufficient demand for services based on our latest wireless technologies, as a result of competition or otherwise, to permit us to recoup or profit from our wireless technology-related capital investments.

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Our businesses are subject to extensive Government regulation and any change in Government policy relating to the telecommunications industry could have a material adverse effect on our results of operations, financial condition and cash flows.

Most of our businesses are subject to extensive governmental supervision and regulation.

Rate Regulation. The Government has periodically reviewed the rates charged by wireless telecommunications service providers and has, from time to time, released public policy guidelines or suggested rate reductions. Although these guidelines or suggestions were not binding, we have implemented some rate reductions in response to them. For example, under the MDDIA, wireless telecommunications service providers are obliged to provide certain benefits, such as discounted rates, to subscribers who subscribe to their service without receiving subsidies. In June 2017, the State Affairs Planning Advisory Committee of Korea announced that it would encourage wireless telecommunications service providers, including us, to increase the applicable discount rate offered to subscribers from 20% to 25%, which we adopted in September 2017, and to offer additional discounts to low income customers, including those on government welfare programs and senior citizen recipients of the basic pension, which we implemented in December 2017 and July 2018, respectively. See “Item 4.B. Business Overview — Law and Regulation — Rate Regulation” and “Item 5.A. Operating Results — Overview — New Rate Regulations.” Such discounts have contributed to a decrease in the monthly revenue per subscriber of our wireless telecommunications services. See “Item 5.A. Operating Results — Overview — Decrease in Monthly Revenue per Subscriber.” The Government may suggest other rate reductions in the future, and any further rate reductions we make in response to such suggestion may adversely affect our results of operations.

Selection of Technology Standards. The Government also plays an active role in the selection of technology to be used by telecommunications operators in Korea. For example, the Government adopted the WCDMA and CDMA2000 technologies as the only standards available in Korea for implementing third generation services. The MSIT may impose similar restrictions on the choice of technology used in future telecommunications services, and it is possible that technologies promoted by the Government in the future may not provide the best commercial returns for us.

Frequency Allocation. The Government sets the policies regarding the use of frequencies and allocates the spectrum of frequencies used for wireless telecommunications. See “Item 4.B. Business Overview — Law and Regulation — Frequency Allocation.” The reallocation of the spectrum to our existing competitors could increase competition among wireless telecommunications service providers, which may have an adverse effect on our business.

MVNOs. Pursuant to the Telecommunications Business Act, certain wireless telecommunications service providers designated by the MSIT, which currently include only us, are required to lease their networks or allow use of their networks (collectively, a “wholesale lease”) to other network service providers, such as an MVNO, that have requested such a wholesale lease in order to provide their own services using the leased networks. To date, thirteen MVNOs have commenced providing wireless telecommunications services using the networks leased from us. We believe that leasing a portion of our bandwidth capacity to an MVNO impairs our ability to use our bandwidth in ways that would generate maximum revenues and strengthens our MVNO competitors by granting them access and lowering their costs to enter into and operate in our markets. Accordingly, our profitability has and may continue to be adversely affected.

Interconnection. Our wireless telecommunications services depend, in part, on our interconnection arrangements with domestic and international fixed-line and other wireless networks. Our interconnection arrangements, including the interconnection rates we pay and interconnection rates we charge, affect our revenues and operating results. The MSIT determines the basic framework for interconnection arrangements, including policies relating to interconnection rates in Korea. The KCC, which determined such basic framework under the previous Government, changed the basic framework for interconnection arrangements several times. We cannot assure you that we will not be adversely affected by the MSIT’s interconnection policies and future changes to such policies. See “Item 4.B. Business Overview — Interconnection — Domestic Calls.”

Regulatory Action. The MSIT may revoke our licenses or suspend any of our businesses if we fail to comply with its rules, regulations and corrective orders, including the rules restricting beneficial ownership and control or

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any violation of the conditions of our licenses. Alternatively, in lieu of suspension of our business, the KCC may levy a monetary penalty of up to 3.0% of the average of our annual revenue for the preceding three fiscal years. For information about the penalties imposed on us for violating Governmental regulations, see “Item 8.A. Consolidated Statements and Other Financial Information — Legal Proceedings — KCC Proceedings.” Such penalties, which may include the revocation of cellular licenses, suspension of business or imposition of monetary penalties by the KCC, could have a material adverse effect on our business. We believe we are currently in compliance with the material terms of all our cellular licenses.

We are subject to additional regulations as a result of our dominant market position in the wireless telecommunications sector, which could harm our ability to compete effectively.

The Government endeavors to promote competition in the Korean telecommunications markets through measures designed to prevent a dominant service provider from exercising its market power and deterring the emergence and development of viable competitors. We have been designated by the MSIT as the “dominant network service provider” in respect of our wireless telecommunications business. As such, we are subject to additional regulations to which certain of our competitors are not subject. For example, under current Government regulations, we must obtain prior approval from the MSIT to raise our existing rates or introduce new rates. Multiple bills have been proposed to the National Assembly to change the approval requirement to a simple reporting requirement, which is the requirement for our competitors. However, there is no assurance as to which of these bills, if any, will be passed. See “Item 4.B. Business Overview — Law and Regulation — Rate Regulation.” The MSIT could also require us to charge higher usage rates than our competitors for future services or to take certain actions earlier than our competitors, as when the KCC required us to introduce number portability earlier than our competitors, KT and LG U+.

We also qualify as a “market-dominating business entity” under the Fair Trade Act, which subjects us to additional regulations and we are prohibited from engaging in any act of abusing our position as a market-dominating entity. See “Item 4.B. Business Overview — Law and Regulation — Competition Regulation.” The additional regulations to which we are subject has affected our competitiveness in the past and may materially hurt our profitability and impede our ability to compete effectively against our competitors in the future.

Declines in the market value of our equity holdings in SK Hynix and the results of operations of SK Hynix could have a material adverse effect on the market price of our common shares and American Depositary Shares (“ADSs”) as well as our results of operation.

As of December 31, 2018, we held a 20.1% equity interest in SK Hynix, which is listed on the KRX KOSPI Market of the Korea Exchange (the “KRX KOSPI Market”) and is one of the world’s largest memory-chip makers by revenue. As of December 31, 2018, the fair value of our holding in SK Hynix was Won 8,839.1 billion. We received dividend payments of Won 146.1 billion in 2018, Won 87.7 billion in 2017 and Won 73.1 billion in 2016 related to such shareholding.

From time to time, the memory semiconductor industry has experienced significant and sometimes prolonged downturns, which often occur in connection with a deterioration of global economic conditions, and is subject to intense competition. For example, SK Hynix and its subsidiaries, on a consolidated basis, incurred net losses of Won 158.8 billion and Won 56.0 billion in 2012 and 2011, respectively, primarily due to increased supply and weak demand for semiconductor products. Although the memory semiconductor industry has recovered since then and SK Hynix has been reporting net profits since 2013, the industry is subject to cyclical fluctuations and we expect that there may be future downturns in the industry. Accordingly, SK Hynix’s operating results would be adversely affected if it fails to compete successfully or decrease manufacturing costs at an adequate level. Our share of any net losses incurred by SK Hynix would be reflected in our income statement as share of losses related to investments in associates.

Accordingly, declines in the market value of our equity holdings in SK Hynix and the results of operations of SK Hynix could have a material adverse effect on the market price of our common shares and ADSs as well as our results of operation.

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We may fail to successfully complete, integrate or realize the anticipated benefits of our new acquisitions or joint ventures, and such transactions may negatively impact our business.

We continue to seek opportunities to develop new businesses that we believe are complementary to our existing product and service portfolio and expand our global business through selective acquisitions. Accordingly, we are often engaged in evaluating potential transactions and other strategic alternatives, some of which may be significant in size. For example, in April 2019, in furtherance of our efforts to enhance the competitiveness of our media business and to promote its future growth, we entered into an agreement with Content Alliance Platform Inc. (“Content Alliance Platform”), a joint venture among the three major terrestrial broadcasters in Korea that operates the mobile over-the-top (“OTT”) service POOQ, pursuant to which we will transfer our mobile OTT service “oksusu” business to Content Alliance Platform to pursue a combination of the two mobile OTT services and participate in a capital increase by Content Alliance Platform through a third-party allotment for a cash consideration of Won 90.0 billion. Furthermore, in April 2019, we signed an agreement to acquire a 34.6% interest in Incross Co., Ltd., a digital advertising company, for an aggregate purchase price of Won 53.5 billion, in light of potential synergies with our media and e-commerce businesses. Also in April 2019, SK Broadband entered into a merger agreement with Tbroad, a leading cable television and other fixed-line telecommunication services provider in Korea, to enhance our capabilities and increase our market share in the fixed-line business. The completion of each of these transactions is subject to regulatory approvals and other closing conditions.

In recent years, we acquired a 46.2% interest in SM Mobile Communications Co., Ltd. (“SM Mobile Communications”) for Won 12.1 billion in 2016, which was subsequently merged into our consolidated subsidiary Dreamus Company (formerly known as IRIVER LIMITED) (“Dreamus”), and we acquired Life Design Company Inc. (formerly known as S.M. Life Design Company Japan Inc.) (“Life Design”) for Won 30.0 billion in 2017, in light of potential synergies that may be achieved through the entertainment business. Furthermore, in order to strengthen our security business and explore potential synergies with our wireless and fixed-line business portfolio, we acquired a 55.0% interest in Life & Security Holdings Co., Ltd. (“LSH”), which owns 100% of ADT CAPS Co., Ltd., a leading Korean physical security service company, and two sister companies, CAPSTEC Co., Ltd. and ADT SECURITY Co., Ltd. (collectively, “ADT Caps”), for Won 696.7 billion in October 2018. We also acquired a 100% interest in SK Infosec Co., Ltd. (“SK Infosec”), Korea’s leading information security company, in a share exchange transaction pursuant to which we issued 1,260,668 treasury shares with an aggregate book value of Won 281.2 billion in exchange for all of the outstanding common shares of SK Infosec in December 2018 from SK Holdings Co., Ltd. (“SK Holdings”), our largest shareholder. In 2018, we also increased our interest in id Quantique SA (“id Quantique”), a leading provider of quantum cryptography solutions for data security based in Switzerland, from 4.6% as of December 31, 2017 to 65.6% as of December 31, 2018, through the acquisition of additional shares with Won 55.2 billion in cash and Won 5.7 billion in contribution-in-kind. For a more detailed description of our recent investments in new businesses, see “Item 5.B. Liquidity and Capital Resources — Capital Requirements — Investments in New Growth Businesses.”

While we are hoping to benefit from a range of synergies from our recent or future acquisitions as well as develop new growth engines for our business, we may not be able to successfully complete or integrate such acquisitions or new businesses and may fail to realize the expected benefits in the near term, or at all. In addition, when we enter into new businesses with partners through joint ventures or other strategic alliances, we and those partners may have disagreements with respect to strategic directions or other aspects of business, or may otherwise be unable to coordinate or cooperate with each other, any of which could materially and adversely affect our operations in such businesses. Our business may be negatively impacted if we fail to successfully integrate or realize the anticipated benefits of such transactions.

Due to the existing high penetration rate of wireless telecommunications services in Korea, we are unlikely to maintain our subscriber growth rate, which could adversely affect our results of operations.

According to data published by the MSIT and the historical population data published by the Ministry of the Interior and Safety, the penetration rate for the Korean wireless telecommunications industry as of December 31, 2018 was approximately 126.1%, which is relatively high compared to many industrialized countries. Therefore, we expect that the penetration rate for wireless telecommunications service in Korea will remain relatively stable. As a result of the already high penetration rate in Korea for wireless telecommunications services coupled with our

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leading market share, we expect our subscriber growth rate to decrease. Slowed growth in the penetration rate without a commensurate increase in revenues through the introduction of new services and increased use of our services by existing subscribers would likely have a material adverse effect on our financial condition, results of operations and cash flows.

Our business and results of operations may be adversely affected if we fail to acquire adequate additional spectrum or use our bandwidth efficiently to accommodate subscriber growth and subscriber usage.

One of the principal limitations on a wireless network’s subscriber capacity is the amount of spectrum available for use by the network. We currently use 10 MHz of bandwidth in the 800 MHz spectrum for our CDMA services, 10 MHz of bandwidth in the 2.1 GHz spectrum for our WCDMA services, 30 MHz of bandwidth in the 2.1 GHz spectrum, 20 MHz of bandwidth in the 800 MHz spectrum, 35 MHz of bandwidth in the 1.8 GHz spectrum and 60 MHz of bandwidth in the 2.6 GHz spectrum for our LTE services, as well as 100 MHz of bandwidth in the 3.5 GHz spectrum for our 5G services. We also plan to use 800 MHz of bandwidth in the 28 GHz spectrum for our 5G services in the future.

The growth of our wireless data businesses has been a significant factor in the increased utilization of our bandwidth, since wireless data applications are generally more bandwidth-intensive than voice services. In particular, the increasing popularity of smartphones and data intensive applications among smartphone users has recently been a major factor for the high utilization of our bandwidth. This trend has been offset in part by the implementation of new technologies, such as our multi-band LTE-A services utilizing 4x4 multiple input multiple output (“MIMO”) technology and our five-band LTE-A technology, which enables more efficient usage of our bandwidth than was possible on our basic LTE network. However, if the current trend of increased data transmission use by our subscribers continues or accelerates, or if the volume of the multimedia content we offer through our wireless data services substantially grows, our bandwidth capacity requirements are likely to increase. While we believe that we can address the capacity constraint issue through system upgrades and efficient allocation of bandwidth, inability to address such capacity constraints in a timely manner may adversely affect our business, results of operations, financial position and cash flows. In the event we are unable to maintain sufficient bandwidth capacity, our subscribers may perceive a general slowdown of wireless telecommunications services. Growth of our wireless telecommunications business will depend in part upon our ability to effectively manage our bandwidth capacity and to implement efficiently and in a timely manner new bandwidth-efficient technologies if they become available. We cannot assure you that bandwidth constraints will not adversely affect the growth of our wireless telecommunications business. Furthermore, we may be required to pay a substantial amount to acquire additional bandwidth capacity in the future in order to meet increasing bandwidth demand and we may not be successful in acquiring the necessary bandwidth to meet such demand, which may adversely affect our financial condition and results of operations.

We rely on key researchers and engineers and senior management, and the loss of the services of any such personnel or the inability to attract and retain them may negatively affect our business.

Our success depends to a significant extent upon the continued service of our research and development and engineering personnel, and on our ability to continue to attract, retain and motivate qualified researchers and engineers. In particular, our focus on leading the market in introducing new services has meant that we must aggressively recruit engineers with expertise in cutting-edge technologies. We also depend on the services of experienced key senior management, and if we lose their services, it would be difficult to find and integrate replacement personnel in a timely manner, or at all.

The loss of the services of any of our key research and development and engineering personnel or senior management without adequate replacement, or the inability to attract new qualified personnel, would have a material adverse effect on our operations.

We need to observe certain financial and other covenants under the terms of our debt instruments, the failure to comply with which would put us in default under those instruments.

Certain of our debt instruments contain financial and other covenants with which we are required to comply on an annual and semi-annual basis. The financial covenants with respect to SK Telecom’s debt instruments include,

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but are not limited to, a maximum net debt-to-EBITDA ratio of 3.50 and a minimum interest coverage ratio of 4.00, each as determined on a separate financial statement basis. The debt arrangements also contain negative pledge provisions limiting our ability to provide liens on our assets as well as cross-default and cross-acceleration clauses, which give related creditors the right to accelerate the amounts due under such debt if an event of default or acceleration has occurred with respect to our existing or future indebtedness, or if any material part of our indebtedness or indebtedness of our subsidiaries is capable of being declared payable before the stated maturity date. In addition, such covenants restrict our ability to raise future debt financing.

If we breach our financial or other covenants, our financial condition will be adversely affected to the extent we are not able to cure such breaches or repay the relevant debt.

We may have to make further financing arrangements to meet our capital expenditure requirements and debt payment obligations.

As a network-based wireless telecommunications provider, we have had, and expect to continue to have, significant capital expenditure requirements as we continue to build out, maintain and upgrade our networks. We spent Won 2,792.4 billion for capital expenditures in 2018. We expect to spend a higher amount for capital expenditures in 2019 compared to 2018 for a range of projects, including investments to expand and further commercialize our newly implemented 5G network, investments to improve and expand our LTE network and LTE-A services, investments to improve and expand our Wi-Fi network, investments to develop our IoT solutions and platform services business portfolio, including AI solutions, investments in research and development of 5G technology, investments in businesses that can potentially leverage our 5G network, and funding for mid- to long-term research and development projects, as well as other initiatives, primarily related to the development of new growth businesses, as well as initiatives related to our ongoing businesses in the ordinary course.

In particular, we continue to make significant capital investments to expand and upgrade our wireless networks in response to growing bandwidth demand by our subscribers. Bandwidth usage by our subscribers has rapidly increased in recent years primarily due to the increasing popularity of smartphones and data intensive applications among smartphone users. If heavy usage of bandwidth-intensive services grows beyond our current expectations, we may need to invest more capital than currently anticipated to expand the bandwidth capacity of our networks or our customers may have a suboptimal experience when using our services. Any of these events could adversely affect our competitive position and have a material adverse effect on our business, financial condition, results of operation and cash flow. For a more detailed discussion of our capital expenditure plans and a discussion of other factors that may affect our future capital expenditures, see “Item 5.B. Liquidity and Capital Resources — Capital Requirements — Capital Expenditures.”

As of December 31, 2018, we had Won 2,175.7 billion in contractual payment obligations due in 2019, which mostly involve repayment of debt obligations and payments related to frequency licenses. See “Item 5.B. Liquidity and Capital Resources — Contractual Obligations and Commitments.”

We have not arranged firm financing for all of our current or future capital expenditure plans and contractual payment obligations. We have, in the past, obtained funds for our proposed capital expenditure and payment obligations from various sources, including our cash flow from operations as well as from financings, primarily debt and equity financings. Any material adverse change in our operational or financial condition could impact our ability to fund our capital expenditure plans and contractual payment obligations. Still volatile financial market conditions may also curtail our ability to obtain adequate funding. Inability to fund such capital expenditure requirements may have a material adverse effect on our financial condition, results of operations and business. In addition, although we currently anticipate that the capital expenditure levels estimated by us will be adequate to meet our business needs, such estimates may need to be adjusted based on developments in technology and markets. In the event we are unable to meet any such increased expenditure requirements or to obtain adequate financing for such requirements, on terms acceptable to us, or at all, this may have a material adverse effect on our financial condition, results of operations and business.

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Termination or impairment of our relationship with a small number of key suppliers for network equipment and for leased lines could adversely affect our results of operations, financial position and cash flows.

We purchase wireless network equipment from a small number of suppliers. To date, we have purchased substantially all of the equipment for our networks from Samsung Electronics Co., Ltd. (“Samsung Electronics”), Ericsson-LG Co., Ltd. (“Ericsson-LG”) and Nokia Siemens Networks B.V. We believe Samsung Electronics currently manufactures approximately half of the wireless handsets sold to our subscribers. Although other manufacturers sell the equipment we require, sourcing such equipment from other manufacturers could result in unanticipated costs in the maintenance and enhancement of our wireless networks. Inability to obtain the equipment needed for our networks in a timely manner may have an adverse effect on our business, financial condition, results of operations and cash flows.

We cannot assure you that we will be able to continue to obtain the necessary equipment from one or more of our suppliers. Any discontinuation or interruption in the availability of equipment from our suppliers for any reason could have an adverse effect on our results of operations. Inability to lease adequate lines at commercially reasonable rates may impact the quality of the services we offer and may also damage our reputation and our business.

Our business relies on technology developed by us, and our business will suffer if we are unable to protect our proprietary rights.

We own numerous patents and trademarks worldwide, and have applications for patents pending in many countries. In addition to active research and development efforts, our success depends in part on our ability to obtain patents and other intellectual property rights covering our services.

We may be required to defend against charges of infringement of patent or other proprietary rights of third parties. Although we have not experienced any significant patent or other intellectual property disputes, we cannot be certain that any significant patent or other intellectual property disputes will not occur in the future. Defending our patent and other proprietary rights could require us to incur substantial expense and to divert significant resources of our technical and management personnel, and could result in our loss of rights to employ certain technologies to provide services.

Malicious and abusive Internet practices could impair our services and we may be subject to significant legal and financial exposure, damage to our reputation and a loss of confidence of our customers.

Our business involves the storage and transmission of large amounts of confidential information, and cybersecurity breaches expose us to a risk of loss of this information, which may lead to improper use or disclosure of such information, ensuing potential liability and litigation, any of which could harm our reputation and adversely affect our business. For example, in July 2011, there was a leak of personal information of subscribers of websites operated by SK Communications Co., Ltd. (“SK Communications”), our consolidated subsidiary. Various lawsuits were filed against SK Communications alleging that the leak was caused by its poor management of subscribers’ personal information. As of December 31, 2018, all twelve of such lawsuits were concluded, with eleven of them ending in final judgments in favor of SK Communications and one withdrawn by the plaintiffs.

Our cybersecurity measures may also be breached due to employee error, malfeasance or otherwise. Instituting appropriate access controls and safeguards across all our information technology infrastructure is challenging. Furthermore, outside parties may attempt to fraudulently induce employees to disclose sensitive information in order to gain access to our data or our customers’ data or accounts, or may otherwise obtain access to such data or accounts. Because the techniques used to obtain unauthorized access, disable or degrade service or sabotage systems change frequently and often are not recognized until launched against a target, we may be unable to anticipate these techniques or to implement adequate preventative measures. If an actual or perceived breach of our cybersecurity occurs or the market perception of the effectiveness of our cybersecurity measures is harmed, we may incur significant legal and financial exposure, including legal claims and regulatory fines and penalties, damage to our reputation and a loss of confidence of our customers, which could have an adverse effect on our business, financial condition and results of operations.

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In addition, our wireless and fixed-line subscribers increasingly utilize our network to access the Internet and, as a consequence, we or they may become victim to common malicious and abusive Internet activities, such as unsolicited mass advertising (i.e., “spam”), hacking of personal information and dissemination of viruses, worms and other destructive or disruptive software. These activities could have adverse consequences on our network and our customers, including degradation of service, excessive call volume to call centers and damage to our or our customers’ equipment and data. Significant incidents could lead to customer dissatisfaction and, ultimately, loss of customers or revenue, in addition to increased costs to us to service our customers and protect our network. Any significant loss of our subscribers or revenue due to incidents of malicious and abusive Internet practices or significant increase in costs of serving those subscribers could adversely affect our business, financial condition and results of operations.

Labor disputes may disrupt our operations.

Although we are not experiencing any significant labor disputes, there can be no assurance that we will not experience labor disputes in the future, including protests and strikes, which could disrupt our business operations and have an adverse effect on our financial condition and results of operation.

Every two years, the union and management negotiate and enter into a new collective bargaining agreement that has a two-year duration, which is focused on employee benefits and welfare. Employee wages are separately negotiated on an annual basis. Although we consider our relations with our employees to be good, there can be no assurance that we will be able to maintain such a working relationship with our employees and will not experience labor disputes resulting from disagreements with the labor union in the future.

Concerns that radio frequency emissions may be linked to various health concerns could adversely affect our business and we could be subject to litigation relating to these health concerns.

In the past, allegations that serious health risks may result from the use of wireless telecommunications devices or other transmission equipment have adversely affected share prices of some wireless telecommunications companies in the United States. In May 2011, the International Agency for Research on Cancer (the “IARC”), a part of the World Health Organization, announced that it has classified radiofrequency electromagnetic fields associated with wireless phone use as possibly carcinogenic to humans, based on an increased risk for glioma, a malignant type of brain cancer. The IARC conducts research on the causes of human cancer and the mechanisms of carcinogenesis and aims to develop scientific strategies for cancer control. We cannot assure you that these health concerns will not adversely affect our business. Several class action and personal injury lawsuits have been filed in the United States against several wireless phone manufacturers and carriers, asserting product liability, breach of warranty and other claims relating to radio transmissions to and from wireless phones. Certain of these lawsuits have been dismissed. We could be subject to liability or incur significant costs defending lawsuits brought by our subscribers or other parties who claim to have been harmed by or as a result of our services. In addition, the actual or perceived risk of wireless telecommunications devices could have an adverse effect on our business by reducing the number of our subscribers or the usage per subscriber.

Our ability to deliver services may be disrupted due to a systems failure, shutdown in our networks or natural disaster.

Our services are currently carried through our wireless and fixed-line networks, which could be vulnerable to damage or interruptions in operations due to fires, floods, earthquakes, power losses, telecommunication failures, network software flaws, unauthorized access, computer viruses and similar events, which may occur from time to time. The occurrence of any of these events could impact our ability to deliver services, we may be liable for damages to our customers caused by such interruptions, our reputation may be damaged and our customers may lose confidence in us, which could have a negative effect on our results of operations.

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Depreciation of the value of the Won against the Dollar and other major foreign currencies may have a material adverse effect on our results of operations and the market value of our common shares and ADSs.

Substantially all of our revenues are denominated in Won. Depreciation of the Won may materially affect our results of operations because, among other things, it causes:

Fluctuations in the exchange rate between the Won and the Dollar will affect the Dollar equivalent of the Won price of the our common shares on the KRX KOSPI Market. These fluctuations also will affect:

If SK Holdings causes us to breach the foreign ownership limitations on our common shares, we may experience a change of control.

The Telecommunications Business Act currently sets a 49.0% limit on the aggregate foreign ownership of our issued shares. Under the Telecommunications Business Act, as amended, a Korean entity, such as SK Holdings, is deemed to be a foreign entity if its largest shareholder (determined by aggregating the shareholdings of such shareholder and its related parties) is a foreigner and such shareholder (together with the shareholdings of its related parties) holds 15.0% or more of the issued voting stock of the Korean entity. As of December 31, 2018, SK Holdings owned 21,624,120 shares of our common stock, or 26.8%, of our issued shares. If SK Holdings were considered to be a foreign shareholder, then its shareholding in us would be included in the calculation of our aggregate foreign shareholding and our aggregate foreign shareholding (based on our foreign ownership level as of December 31, 2018, which we believe was 41.8%) would exceed the 49.0% ceiling on foreign shareholding. As of December 31, 2018, the two largest foreign shareholders of SK Holdings each held a 3.5% stake therein.

If our aggregate foreign shareholding limit is exceeded, the MSIT may issue a corrective order to us, the breaching shareholder (including SK Holdings if the breach is caused by an increase in foreign ownership of SK Holdings) and the foreign shareholder which owns in the aggregate 15.0% or more of SK Holdings. Furthermore, if SK Holdings is considered a foreign shareholder, it will be prohibited from exercising its voting rights with respect to the shares held in excess of the 49.0% ceiling, which may result in a change in control of us. In addition, the MSIT will be prohibited from granting us licenses or permits necessary for entering into new telecommunications businesses until our aggregate foreign shareholding is reduced to below 49.0%. For a description of further actions that the MSIT could take, see “Item 4.B. Business Overview — Law and Regulation — Foreign Ownership and Investment Restrictions and Requirements.”

Risks Relating to Korea

Unfavorable financial and economic developments in Korea may have an adverse effect on us.

We are incorporated in Korea, and a substantial portion of our operations and assets are located in Korea. As a result, we are subject to political, economic, legal and regulatory risks specific to Korea. The economic indicators in Korea in recent years have shown mixed signs, and future growth of the Korean economy is subject to many factors beyond our control, including developments in the global economy.

In recent years, adverse conditions and volatility in the worldwide financial markets, fluctuations in oil and commodity prices, increases in interest rates globally and the general weakness of the global economy have contributed to the uncertainty of global economic prospects in general and have adversely affected, and may

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continue to adversely affect, the Korean economy. The value of the Won relative to major foreign currencies has fluctuated significantly. Furthermore, as a result of adverse global and Korean economic conditions, there has been volatility in the stock prices of Korean companies in recent years. Future declines in the Korea Composite Stock Price Index (known as the “KOSPI”) and large amounts of sales of Korean securities by foreign investors and subsequent repatriation of the proceeds of such sales may continue to adversely affect the value of the Won, the foreign currency reserves held by financial institutions in Korea and the ability of Korean companies to raise capital. Any future deterioration of the Korean or global economy could adversely affect our business, financial condition and results of operations.

Developments that could have an adverse impact on Korea’s economy include:

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Escalations in tensions with North Korea could have an adverse effect on us and the market value of our common shares and ADSs.

Relations between Korea and North Korea have been tense throughout Korea’s modern history. The level of tension between the two Koreas has fluctuated and may increase abruptly as a result of future events. In particular, there have been heightened security concerns in recent years stemming from North Korea’s nuclear weapon and ballistic missile programs as well as its hostile military actions against Korea. Some of the significant incidents in recent years include the following:

North Korea’s economy also faces severe challenges, which may further aggravate social and political pressures within North Korea. Although bilateral summit meetings were held between Korea and North Korea in April, May and September 2018 and between the United States and North Korea in June 2018 and February 2019, there can be no assurance that the level of tensions affecting the Korean peninsula will not escalate in the future. Any increase in tensions, which may occur, for example, if North Korea experiences a leadership crisis, high-level contacts between Korea or the United States and North Korea break down or further military hostilities occur, could

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have a material adverse effect on our business, results of operations and financial condition and the market value of our common shares and ADSs.

Korea’s legislation allowing class action suits related to securities transactions may expose us to additional litigation risk.

The Securities-related Class Action Act of Korea enacted in January 2004 allows class action suits to be brought by shareholders of companies (including us) listed on the KRX KOSPI Market for losses incurred in connection with purchases and sales of securities and other securities transactions arising from (1) false or inaccurate statements provided in the registration statements, prospectuses, business reports, audit reports, semi-annual or quarterly reports and material fact reports and omission of material information in such documents, (2) insider trading, (3) market manipulation and (4) unfair trading. This law permits 50 or more shareholders who collectively hold 0.01% of the shares of a company to bring a class action suit against, among others, the issuer and its directors and officers. Because of the relatively recent enactment of the act, there is not enough judicial precedent to predict how the courts will apply the law. Litigation can be time-consuming and expensive to resolve, and can divert management time and attention from the operation of a business. We are not aware of any basis upon which such suit may be brought against us, nor are any such suits pending or threatened. Any such litigation brought against us could have a material adverse effect on our business, financial condition and results of operations.

There are special risks involved with investing in securities of Korean companies, including the possibility of restrictions being imposed by the Government in emergency circumstances.

As we are a Korean company and operate in a business and cultural environment that is different from that of other countries, there are risks associated with investing in our securities that are not typical for investments in securities of companies in other jurisdictions.

Under the Korean Foreign Exchange Transactions Act, if the Government deems that certain emergency circumstances, including a significant disruption in the international balance of payments and international financial markets or extreme difficulty in carrying out currency, exchange rate or other macroeconomic policies due to the movement of capital between Korea and other countries, are likely to occur, it may impose any necessary restriction such as requiring Korean or foreign investors to obtain prior approval from the Ministry of Economy and Finance (the “MOEF”) for the acquisition of Korean securities or for the repatriation of interest, dividends or sales proceeds arising from Korean securities or from disposition of such securities or other transactions involving foreign exchange. See “Item 10.D. Exchange Controls — Korean Foreign Exchange Controls and Securities Regulations.”

Risks Relating to Securities

Sales of our shares by SK Holdings and/or other large shareholders may adversely affect the market value of our common shares and ADSs.

Sales of substantial amounts of our common shares, or the perception that such sales may occur, could adversely affect the prevailing market value of our common shares or ADSs or our ability to raise capital through an offering of our common shares.

As of December 31, 2018, SK Holdings owned 26.8% of our total issued common shares and has not agreed to any restrictions on its ability to dispose of our shares. See “Item 7.A. Major Shareholders.” We can make no prediction as to the timing or amount of any sales of our common shares. We cannot assure you that future sales of our common shares, or the availability of our common shares for future sale, will not adversely affect the prevailing market value of our common shares or ADSs from time to time.

If an investor surrenders his or her ADSs to withdraw the underlying shares, he or she may not be allowed to deposit the shares again to obtain ADSs.

Under the deposit agreement, holders of our common shares may deposit those shares with the ADR depositary’s custodian in Korea and obtain ADSs, and holders of ADSs may surrender ADSs to the ADR depositary and receive our common shares. However, under the terms of the deposit agreement, as amended, the depositary

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bank is required to obtain our prior consent to any such deposit if, after giving effect to such deposit, the total number of our common shares represented by ADSs, which was 8,022,140 shares as of March 31, 2019, exceeds a specified maximum, subject to adjustment under certain circumstances. In addition, the depositary bank or the custodian may not accept deposits of our common shares for issuance of ADSs under certain circumstances, including (1) if it has been determined by us that we should block the deposit to prevent a violation of applicable Korean laws and regulations or our articles of incorporation or (2) if a person intending to make a deposit has been identified as a holder of at least 3.0% of our common shares. It is possible that we may not give the consent. Consequently, an investor who has surrendered his or her ADSs and withdrawn the underlying shares may not be allowed to deposit the shares again to obtain ADSs.

An investor in our ADSs may not be able to exercise preemptive rights for additional new shares and may suffer dilution of his or her equity interest in us.

The Korean Commercial Code and our articles of incorporation require us, with some exceptions, to offer shareholders the right to subscribe for new shares in proportion to their existing ownership percentage whenever new shares are issued. If we offer a right to subscribe for additional new common shares or any other rights of similar nature, the ADR depositary, after consultation with us, may make the rights available to an ADS holder or use reasonable efforts to dispose of the rights on behalf of the ADS holder and make the net proceeds available to the ADS holder. The ADR depositary, however, is not required to make available to an ADS holder any rights to purchase any additional shares unless it deems that doing so is lawful and feasible and:

We are under no obligation to file any registration statement with respect to any ADSs. If a registration statement is required for an ADS holder to exercise preemptive rights but is not filed by us, the ADS holder will not be able to exercise his or her preemptive rights for additional shares. As a result, ADS holders may suffer dilution of their equity interest in us.

Short selling of our ADSs by purchasers of securities convertible or exchangeable into our ADSs could materially adversely affect the market price of our ADSs.

SK Holdings, through one or more special purpose vehicles, has engaged and may in the future engage in monetization transactions relating to its ownership interest in us. These transactions have included and may include offerings of securities that are convertible or exchangeable into our ADSs. Many investors in convertible or exchangeable securities seek to hedge their exposure in the underlying equity securities at the time of acquisition of the convertible or exchangeable securities, often through short selling of the underlying equity securities or similar transactions. Since a monetization transaction could involve debt securities linked to a significant number of our ADSs, we expect that a sufficient quantity of ADSs may not be immediately available for borrowing in the market to facilitate settlement of the likely volume of short selling activity that would accompany the commencement of a monetization transaction. This short selling and similar hedging activity could place significant downward pressure on the market price of our ADSs, thereby having a material adverse effect on the market value of ADSs owned by you.

A holder of our ADSs may not be able to enforce a judgment of a foreign court against us.

We are a corporation with limited liability organized under the laws of Korea. Substantially all of our directors and officers and other persons named in this document reside in Korea, and all or a significant portion of the assets of our directors and officers and other persons named in this document and substantially all of our assets are located in Korea. As a result, it may not be possible for holders of our ADSs to effect service of process within the United States, or to enforce against us any judgments obtained from the United States courts based on the civil liability provisions of the federal securities laws of the United States. There is doubt as to the enforceability in Korea, either in original actions or in actions for enforcement of judgments of United States courts, of civil liabilities predicated on the United States federal securities laws.

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We are generally subject to Korean corporate governance and disclosure standards, which may differ from those in other countries.

Companies in Korea, including us, are subject to corporate governance standards applicable to Korean public companies, which may differ in some respects from standards applicable in other countries, including the United States. As a reporting company registered with the SEC and listed on the New York Stock Exchange (the “NYSE”), we are subject to certain corporate governance standards as mandated by the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”). However, foreign private issuers, including us, are exempt from certain corporate governance requirements under the Sarbanes-Oxley Act or under the rules of the NYSE. There may also be less publicly available information about Korean companies, such as us, than is regularly made available by public or non-public companies in other countries. Such differences in corporate governance standards and less public information available could result in corporate governance practices or disclosures that are perceived as less than satisfactory by investors in certain countries.

As Korea’s first wireless telecommunications service provider, we have a recognized history of leadership and innovation in the domestic telecommunications sector. Today, we remain Korea’s leading wireless telecommunications services provider and have continued to pioneer the commercial development and implementation of state-of-the-art wireless technologies. We had 30.9 million wireless subscribers, including MVNO subscribers leasing our networks, as of December 31, 2018, representing a market share of 47.2%, the largest market share among Korean wireless telecommunications service providers. We believe we are also a leader in developing new products and services that reflect the increasing convergence of telecommunications technologies, as well as the growing synergies between the telecommunications sector and other industries, and are well-positioned to become Korea’s leading platform service provider through our next-generation growth businesses in IoT solutions, media, e-commerce, security and other innovative products offered through our platform services, including AI solutions.

In February 2012, we acquired an equity stake in SK Hynix, one of the world’s largest memory-chip makers by revenue, for an aggregate purchase price of Won 3.4 trillion, and became its largest shareholder. As of December 31, 2018, we held a 20.1% equity interest in SK Hynix.

On March 31, 2019, we had a market capitalization of approximately Won 20.3 trillion (US$17.9 billion, as translated at the noon buying rate of March 31, 2019) or approximately 1.4% of the total market capitalization on the KRX KOSPI Market, making us the 11th largest company listed on the KRX KOSPI Market based on market capitalization on that date. Our ADSs, each representing one-ninth of one share of our common stock, have traded on the NYSE since June 27, 1996.

We are a corporation with limited liability organized under the laws of Korea. We established our telecommunications business in March 1984 under the name Korea Mobile Telecommunications Co., Ltd. We changed our name to SK Telecom Co., Ltd., effective March 21, 1997. In January 2002, we merged with Shinsegi Telecom Co., Ltd. (“Shinsegi”), which was then the third-largest wireless telecommunications service provider in Korea. Our registered office is at SK T-Tower, 65, Eulji-ro, Jung-gu, Seoul 04539, Korea and our telephone number is +82-2-6100-2114. Our website address is http://www.sktelecom.com.

The SEC maintains a website (http://www.sec.gov), which contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC.

Korean Telecommunications Industry

Established in March 1984, we became the first wireless telecommunications service provider in Korea. We remained the sole provider of wireless telecommunications services until April 1996, when Shinsegi commenced cellular service. The Government began to introduce competition into the fixed-line and wireless telecommunications services markets in the early 1990’s. During this period, the Government allowed new competitors to enter the fixed-line sector, sold a controlling stake in us to the SK Group, and granted a cellular

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license to our first competitor, Shinsegi. In October 1997, three additional companies began providing wireless telecommunications services under Government licenses to provide wireless telecommunications services. In 2000 and 2001, the Korean wireless telecommunications market experienced significant consolidation. In January 2002, Shinsegi was merged into us. Additionally, two of the other wireless telecommunications services providers merged.

There are currently three mobile network operators in Korea: our company, KT and LG U+. As of December 31, 2018, the market share of the Korean wireless telecommunications market, in terms of number of subscribers, of KT and LG U+ was approximately 31.6% and 21.2%, respectively (compared to our market share of 47.2%), each including MVNO subscribers leasing the respective networks. As of December 31, 2018, MVNOs had a combined market share of 12.2%, of which MVNOs leasing our networks represented 5.4%, MVNOs leasing KT’s networks represented 5.7% and MVNOs leasing LG U+’s networks represented 1.2%.

Telecommunications industry growth in Korea has been among the most rapid in the world, with fixed-line penetration being under five lines per 100 population in 1978 and increasing to 47.9 lines per 100 population as of December 31, 2006 before decreasing to 27.7 lines per 100 population as of December 31, 2018, and wireless penetration increasing from 7.0 subscribers per 100 population in 1996 to 126.1 subscribers per 100 population as of December 31, 2018. The table below sets forth certain subscription and penetration information regarding the Korean telecommunications industry as of the dates indicated:

Since the introduction of short text messaging in 1998, Korea’s wireless data market has grown rapidly. This growth has been driven, in part, by the rapid development of wireless Internet service since its introduction in 1999 and the implementation of LTE technology providing for fast data transmission speeds and large data transmission capacity. As of December 31, 2018, approximately 58.1 million Korean wireless subscribers owned Internet-enabled handsets capable of accessing wireless Internet services, including 50.8 million subscribers that own smartphones that have direct access to the Internet using mobile Internet technology. The table below sets forth certain penetration information regarding the number of Internet-enabled handsets, smartphones and wireless subscribers in Korea as of the dates indicated:

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In addition to its well-developed wireless telecommunications sector, Korea has one of the largest Internet markets in the Asia Pacific region. From the end of 2005 to the end of 2018, the number of broadband Internet access subscribers increased from approximately 12.2 million to approximately 21.3 million. In connection with such growth in broadband Internet usage, the number of IPTV subscribers has also increased rapidly. The table below sets forth certain information regarding broadband Internet access subscribers and IPTV subscribers as of the dates indicated:

Overview

We are Korea’s leading wireless telecommunications services provider and continue to pioneer the commercial development and implementation of state-of-the-art wireless and fixed-line technologies and services as well as develop our next-generation growth businesses in IoT solutions, media, e-commerce, security and other innovative products offered through our platform services, including AI solutions. Our operations are reported in four segments:

Our Business Strategy

We believe that the current trends in the Korean telecommunications industry are characterized by technological change, evolving consumer needs and increasing digital convergence. Against the backdrop of these industry trends, we aim to maintain our leading position in the Korean market for wireless telecommunications services and actively develop our next-generation growth businesses in IoT solutions, media and e-commerce and other innovative products offered through our platform services. We plan to further utilize our big data analysis capabilities to create products and services that are tailored to our customers’ evolving needs, as well as incorporate AI capabilities directly into many of the products and services we offer.

Our corporate vision is to “Create Customer’s Pride” and provide enhanced customer value through integrated products and services that better meet our customers’ needs. To take advantage of these industry trends and further realize our corporate vision and become a leader in information and communication technologies (“ICT”), we have undertaken the following strategic initiatives.

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Cellular Services

We offer wireless voice and data transmission services, sell wireless devices and provide IoT solutions and innovative platform services through our cellular services segment. Our wireless voice and data transmission services are offered through our backbone networks that collectively can be accessed by approximately 99.0% of the Korean population. We had 30.9 million wireless subscribers, including MVNO subscribers leasing our networks, as of December 31, 2018, representing a market share of 47.2%, the largest market share among Korean wireless telecommunications service providers. The table below sets forth the number of subscribers, including subscribers of MVNOs that lease our wireless networks, using our various digital wireless networks as of the dates indicated:

Following the commencement of the operation of our 5G network on a limited basis for business customers in December 2018, we launched wireless services using the 5G network in April 2019, and we plan to continue expanding our 5G network coverage and enhancing service quality.

In 2018, 2017 and 2016, our cellular services segment revenue was Won 12,378.9 billion, Won 13,262.1 billion and Won 13,004.9 billion, respectively, representing 73.3%, 75.7% and 76.1%, respectively, of our consolidated revenue.

Wireless Services

We offer wireless voice transmission and data transmission services to our subscribers through our backbone networks. Our wireless telecommunications services are available to our subscribers receiving service under the SK

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Telecom brand. In addition, customers can obtain wireless telecommunications services that operate on our network from MVNOs that lease our wireless networks. We derive revenues from our wireless telecommunications service principally through monthly plan-based fees as described in “— Rate Plans” below.

We provide a voice-over-LTE service, known as our “HD Voice” service, to all of our LTE subscribers featuring high-quality voice transmission, fast call connection, voice-to-video call switching and digital content sharing during calls. We also offer our subscribers a wide range of wireless data transmissions services. Our messaging service allows our subscribers to send and receive text, graphic, audio and video messages. In addition, our subscribers can access a wide variety of digital content and services through mobile applications providing music, video, gaming, news, commerce and financial services as well as solutions that enable subscribers to access the Internet and e-mail. We intend to continue to build our wireless data services as a platform for growth, extending our portfolio of wireless data services and developing new content for our subscribers.

Through service agreements with various foreign wireless telecommunications service providers, we offer cellular global roaming services, branded as our “T-Roaming” service. Global roaming services allow subscribers traveling abroad to make and receive calls using their regular mobile phone numbers. In addition, we provide global roaming service to foreigners traveling to Korea. In such cases, we generally receive a fee from the traveler’s local wireless telecommunications service provider.

Through SK Telink, we also operate our MVNO business under the brand “SK 7Mobile,” which we believe offers excellent quality at reasonable rates utilizing SK Telecom’s wireless networks. SK Telink is focused on developing low-cost distribution channels and targeting niche customer segments that have a lower average revenue per user than that of SK Telecom’s subscriber base.

In addition, we provide interconnection service to connect our networks to domestic and international fixed-line and other wireless networks. See “— Interconnection” below.

Wireless Device Sales

We offer several categories of wireless devices, including smartphones and basic phones, tablets and other Internet access devices and wearable devices that are sold through an extensive distribution network, which consists of authorized exclusive dealers and independent retailers, as well as branch offices and stores directly operated by us through our wholly-owned subsidiary, PS&Marketing Co., Ltd. (“PS&Marketing”). As of December 31, 2018, approximately 24.0 million, or 77.6%, of our subscribers (including MVNO subscribers leasing our networks) owned smartphones that have direct access to the Internet compared to approximately 23.0 million subscribers, or 76.1%, as of December 31, 2017. We purchase a substantial majority of our wireless devices from Samsung Electronics, Apple and LG Electronics.

Smartphones and Basic Phones.    We offer smartphones that are enabled to utilize our digital wireless networks and run on various operating systems, such as Apple iOS and Google Android. We also offer basic phones that have the ability to access wireless Internet services.

Tablets and Other Internet Devices.    We offer tablets which can access the Internet via our digital wireless networks and a Wi-Fi connection. The tablets run primarily on the Apple iOS and Google Android operating systems. In addition, we also offer “T Pocket-Fi” devices that provide a mobile LTE connection and are capable of connecting multiple Wi-Fi enabled devices to the Internet at one time. We offer targeted rate plans for our T Pocket-Fi device. See “— Rate Plans” below.

Wearable Devices.    We offer various wearable devices including smart watches and “T kids’ phone-Joon.” These devices utilize our digital wireless networks and have specific features for the relevant target customer. For example, T kids’ phone-Joon is a wearable phone targeted towards children and provides simple calling, messaging and chat services as well as global positioning system (“GPS”) tracking capabilities. We offer targeted rate plans that are specific to these wearable devices. See “— Rate Plans” below.

IoT Solutions

Through our IoT solutions business, we provide network access and enhanced services to support telemetry-type applications, which are characterized by machine-to-machine (“M2M”) wireless connections, to business

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customers, and a home monitoring service platform for residential customers. In order to promote the growth of our IoT solutions business, we deployed networks nationwide that are designed to support IoT devices, namely our high-speed LTE-M network in March 2016 and our LoRa network in July 2016. In April 2018, we increased the battery efficiency of our IoT devices by launching our LTE Cat.M1 technology and further enhanced our competitiveness in this business.

We provide network access and customized IoT solutions to our business customers. Our M2M services support devices that are used in a variety of market segments, including retail, utilities, security, automotive, agriculture and data analytics. For example, our Cloud Energy Management Solution (“Cloud EMS”) business provides a one-stop cloud computing-based energy management platform that collects and analyzes energy usage data from business customers and offers solutions to optimize and reduce their energy consumption. As of December 31, 2018, Cloud EMS had approximately 200 customers, mostly from energy-intensive industries such as the petrochemical and cement industries. With the launch of our 5G network in December 2018, we are focusing on developing IoT solutions for business customers that can leverage our 5G technology, such as smart factory, smart broadcasting and smart office solutions. In furtherance of such efforts, the Government and a number of private companies in the ICT sector, including us, formed a 5G Smart Factory Alliance in December 2018 in order to standardize and test the interoperability of technologies related to smart factory solutions based on our 5G network. In December 2018, we also launched our 5G-AI Machine Vision solution, which utilizes cameras to monitor the customer’s manufacturing process and transmits images or videos to a cloud server through our 5G network to instantaneously detect manufacturing defects using AI technology.

We also provide “Smart Home,” a mobile application-based home monitoring service for residential customers. Smart Home is a paid subscription service available not only to our wireless and fixed-line service subscribers but also to subscribers of our competitors’ wireless and fixed-line services. Through partnerships with more than 50 construction companies, we provided built-in Smart Home services to more than 58,000 homes as of December 31, 2018. Through Smart Home, users can control and monitor their home environment from their mobile devices and enhance the safety and convenience of their daily lives.

Platform Services

Through our platform services business, we seek to provide innovative products and services that meet our customers’ evolving needs in an increasingly connected world. For example, we provide location-based services such as T map, which we provide to our and our competitors’ wireless subscribers free of charge. T map uses GPS technology to transmit driving directions, real-time traffic updates and emergency rescue assistance to wireless devices. As of December 31, 2018, there were approximately 11.3 million monthly average users of our T map service. In September 2017, we also integrated NUGU, described in more detail below, into our T map service enabling users to use voice commands to operate their mobile devices while driving. In May 2018, we added calling and text messaging functions to the NUGU capabilities available on T map to enhance the convenience and safety of T map users. T map also offers a taxi-hailing service called “T map Taxi.” In January 2019, we signed an agreement with Grab, the leading ride-hailing service provider in Southeast Asia, to establish a joint venture called Grab Geo Holdings. Through this joint venture, we plan to launch a navigation service for Grab drivers based on T map’s key technologies, including big data analysis algorithms and ultra-precise GPS solutions.

We also offer AI solutions through our platform services business. For example, in September 2016, we launched NUGU, the first intelligent virtual assistant service launched in Korea with Korean language capabilities based on advanced voice recognition technologies. NUGU currently offers a wide range of services including music streaming, connectivity with “Smart Home” and other IoT solutions for the home, food deliveries, and informational and other personal assistance services, and we plan to continually enhance its functionalities through software updates. Through cloud-based deep-learning technology, NUGU is designed to evolve on its own as it collects more data about its users over time. We have integrated NUGU into our T map service as discussed above as well as our B tv service as further discussed in “— Fixed-line Telecommunication Services — Advanced Media Platform (including IPTV and Mobile OTT Services).” In July 2018, we launched “NUGU candle,” an AI light that offers NUGU-based services and changes its color and brightness based on the user’s needs and preferences. In October 2018, we launched “NUGU developers,” a platform on which third-party developers can create and launch

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new services based on NUGU technology. We continue to explore ways in which we can leverage our NUGU technology to enhance our existing products and services.

We also provide a “T phone” service, which offers our customers a number of convenient call functions, such as a spam-call blocking function and a search function that informs customers of the phone numbers of shops, hospitals and other facilities closest to the customer’s current location.

Rate Plans

We offer our wireless telecommunications services on both a postpaid and prepaid basis. Approximately 93.1% of our subscribers received our wireless telecommunications services on a postpaid basis as of December 31, 2018. Postpaid accounts primarily represent retail subscribers under contract with SK Telecom under which a subscriber is billed in advance a monthly fixed rate in return for a monthly network service allowance and usage for outgoing voice calls and wireless data services beyond the allowance is billed in arrears, where payment of the total amount of the bill is due at the end of the month. The standard contract period for our rate plans is 24 months, although our subscribers have the option to enter into shorter term contracts or no fixed-term contract at all. We provide various subsidies and discounts, including handset subsidies, depending on the length of the contract and the subscriber’s chosen rate plan. Our prepaid service enables individuals to obtain wireless telecommunications services without a fixed-term contract by paying for all services in advance according to expected usage. We do not charge our customers for incoming calls, although we do receive interconnection charges from KT and other companies for calls from the fixed-line network terminating on our networks and interconnection revenues from other wireless network operators. See “— Interconnection” below.

We also charge our customers a 10.0% value-added tax, which is included in the price of all of our rate plans. We can offset the value-added tax we collect from our customers against value-added tax refundable to us by the Korean tax authorities. We remit taxes we collect from our customers to the Korean tax authorities. We record revenues in our financial statements net of such taxes.

Basic Rate Plans.    We offer various postpaid account plans for smartphones and basic phones that are designed to meet a wide range of subscriber needs and interests. As of December 31, 2018, approximately 17 million subscribers have subscribed to our “T” plans or “Band Data” plans, which are our representative smartphone rate plans featuring unlimited domestic voice minutes and text messaging and a fixed or unlimited data transmission allowance per month that range from Won 33,000 to Won 100,000 per month and from Won 32,890 to Won 110,000 per month, respectively. Our “Voice Free” plans are available for our basic phones and feature a fixed allowance of voice minutes and 50 text messages per month with rates that range from Won 20,900 to Won 103,400 per month. We also offer a standard rate plan for Won 12,100 per month, through which the subscriber is charged per usage amount, other than on text message usage up to 50 messages per month. In April 2019, we introduced our rate plans for our 5G services featuring unlimited domestic voice minutes and text messaging and a fixed or unlimited data transmission allowance per month that range from Won 55,000 to Won 125,000 per month.

In addition, we provide a variety of differentiated rate plans for our customer segments such as our “0” plans for smartphone users who are 24 years old or younger featuring greater data allowance and premium benefits tailored for younger demographics, our “Cookiz-mini” plan for children who are 12 years old or younger, our “T Global” rate plans for foreigners featuring unlimited domestic voice minutes and text messaging, a fixed allowance of international voice minutes and data transmission per month and our “Weekend Ting” rate plans for teenagers featuring more data transmission allowance on weekends. We also provide “T Signature” rate plans for customers seeking unlimited wireless data usage for fixed rates and a multitude of other premium benefits such as mobile device insurance coverage and mobile device upgrades.

For our T Pocket-Fi device, we provide a fixed monthly data transmission allowance of 10 GB for Won 16,500 per month and 20 GB for Won 24,750 per month. With respect to the wearable devices that we offer, we offer targeted rate plans for smart watches that range from Won 11,000 to Won 12,100 per month, and the “Cookiz” rate plans for our T kids’ phone-Joon devices that range from Won 8,800 to Won 19,800 per month.

Data Add-on Rate Plans.    We offer a variety of optional “add-on” rate plans that are designed to meet a wide range of subscriber needs with respect to increased data usage that followed the widespread use of smartphones and

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faster transmission speeds made possible by LTE technology. For example, we offer data plans that offer unlimited data based on time, place and occasion such as our “Subway Free” plan, which offers unlimited wireless data usage on subway platforms and inside subways and our “Commuter Free” plan, which offers unlimited wireless data usage during rush hour, each for a fixed rate of Won 9,900 per month. For certain rate plan subscribers, we also offer a daily allowance of 1 GB of oksusu access and a monthly allowance of 8,000 points to purchase media content on oksusu through our “oksusu Safe” plan for Won 5,500 or Won 8,800 per month, depending on the subscribers’ basic rate plan. “Safe Option Premium” offers an additional daily data transmission allowance of 50 MB to subscribers who have used the maximum data transmission on their existing plan without incurring additional data transmission fees for a fixed rate of Won 8,800 per month. We also offer “T Data Coupons,” through which subscribers can purchase a fixed amount of data for a fixed price and can also be sent as “gifts” to family and friends that need additional data allowance. We believe that our data add-on rate plan offerings have contributed to the increase in data usage to 7.1 GB of average monthly data usage per LTE subscriber as of December 31, 2018 from 6.0 GB as of December 31, 2017.

Roaming Plans.    We offer roaming services in more than 200 countries. We provide an automatic roaming service called “Safe Automatic T Roaming,” which provides 30 minutes of voice calls per day (including three minutes of free voice calls) for a maximum of Won 10,000 (with voice calls in excess of 30 minutes per day incurring additional charges) and data transmission at a rate of Won 563 per MB with a daily data transmission charge ceiling of Won 5,000. We also provide fixed-rate international roaming plans such as our “baro OnePass” plans, which provide data roaming services at different speeds depending on usage amount for Won 9,900 to Won 16,500 per day and are available in more than 160 countries, depending on the specific plan chosen, and our “baro” plans, which provide fixed data transmission allowances that can be used over a specified number of days in 98 countries in Asia, the Americas, Europe and Oceania, ranging from Won 29,000 to Won 59,000. With respect to international calls placed by a subscriber, unless the subscriber uses one of our fixed-rate international roaming plans, we bill the subscriber the international rate charged by the Korean international telephone service provider through which the call is routed. We remit to that provider the international charge less our usage charges. See “— Interconnection” below.

Digital Wireless Network

We offer wireless voice and data transmission services throughout Korea using digital wireless networks, primarily consisting of our 5G network, LTE network, WCDMA network, CDMA network, Wi-Fi network and LoRa network. We continually upgrade and increase the capacity of our wireless networks to keep pace with advancements in technology, the growth of our subscriber base and the increased usage of voice and wireless data services by our subscribers. For more information about our capital expenditures relating to our wireless networks, see “Item 5.B. Liquidity and Capital Resources — Capital Requirements — Capital Expenditures.”

5G Network.    We began the operation of our 5G network in December 2018 on a limited basis for business customers, beginning with a few major commercial districts in Seoul and other metropolitan areas. In April 2019, we launched wireless service plans using the 5G network following the commencement of sales of the first 5G-compatible smartphones, and we are in the process of expanding our 5G network coverage, beginning with the Seoul metropolitan area and other major cities. Our 5G services provide a maximum data transmission speed of 2.7 Gbps.

LTE Network.    LTE technology has become widely accepted globally as the standard fourth generation technology and enables data to be transmitted at speeds faster than our CDMA and WCDMA networks. Since first commencing our LTE services in July 2011 and LTE-A services, which use carrier aggregation technology that combines spectrum frequencies to improve data transmission speeds, in June 2013, we have developed and launched various upgraded LTE networks and services providing faster network speeds, enhanced connectivity and broader coverage areas. In February 2018, we launched four-band LTE-A services utilizing 4x4 MIMO technology providing for data transmission speeds of up to 1 Gbps, and in March 2019, we commenced five-band LTE-A services using 4x4 MIMO technology that provide data transmission speeds of up to 1.2 Gbps. With these developments in LTE technology, our LTE penetration increased to 80.3% as of December 31, 2018 compared to 49.3% as of December 31, 2013. We expect that wireless services based on LTE technology will continue to be used broadly by our users in the near future, as we and our competitors continue to build up 5G networks and

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services and wireless service users gradually migrate to the 5G network over time, and plan to continue to deploy improved LTE-A technology to increase the maximum data transmission speed of our services. For M2M connections relating to our IoT solutions, we launched our LTE-M services at speeds of up to 10 Mbps in March 2016, as well as our LTE Cat.M1 services at speeds of up to 0.03 Mbps in April 2018. Our continued upgrades to our LTE technology enables even faster data transmission speeds, as shown below.

We believe that our advanced LTE technology and dense network infrastructure enable us to provide the fastest LTE data transmission network nationwide. In December 2018, the MSIT announced that our LTE network provided the fastest upload and download speeds among the three mobile network operators, KT, LG U+ and us. The nationwide average download speed of our LTE network was 195.5 Mbps compared to 144.5 Mbps for KT’s LTE network and 112.0 Mbps for LG U+’s LTE network.

The faster data transmission speed of our LTE network has allowed us to offer significantly improved wireless data transmission services, providing our subscribers with faster wireless access to multimedia content. We have been building new access networks and evolved packet cores for our LTE network, while we utilize our existing WCDMA network for other parts of our LTE network.

CDMA and WCDMA Networks.    CDMA technology is a continuous digital transmission technology that accommodates higher throughput than analog technology by using various coding sequences to allow concurrent transmission of voice and data signals for wireless communication. In January 1996, we launched our first wireless network based on CDMA technology and became the world’s first to commercialize CDMA cellular service. In February 2019, we announced our plan to phase out CDMA services by the end of 2019.

WCDMA technology enables us to offer significantly faster and higher-quality voice and data transmission and supports more sophisticated wireless data transmission services than is possible through our CDMA network. Since first commencing our WCDMA services in Seoul in 2003, we have expanded our WCDMA network nationwide and implemented various technologies to improve data transmission speeds within our WCDMA network.

Wi-Fi Network.    Wi-Fi technology enables our subscribers with Wi-Fi-capable devices such as smartphones, laptops and tablet computers to access mobile Internet. We started to build Wi-Fi access points in 2010 and, as of December 31, 2018, we had more than 130,000 Wi-Fi access points in public areas such as shopping malls, restaurants, coffee shops, subways and airports where, generally, the demand for high-speed wireless Internet service is high. While each Wi-Fi access point typically has a radius of approximately 20-30 meters, some of our Wi-Fi hot zones, which have multiple Wi-Fi access points, including those installed at public transportation facilities and amusement parks, have much wider service areas.

LoRa Networks.    A Low-Power Wide-Area network based on LoRa technology is a type of telecommunications network designed to support communication among IoT devices. It can transmit data over tens of kilometers while consuming much less power than LTE networks, lowering costs for connectivity as well as lowering battery power usage. We completed the nationwide deployment of our LoRa network in July 2016. We expect that our LoRa network will provide the infrastructure necessary for the growth of not only our own IoT solutions business but also the IoT industry as a whole.

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Network Infrastructure

The principal components of our wireless networks are:

As of December 31, 2018, our 5G, LTE, WCDMA, CDMA and WiBro networks had an aggregate of 54,203 cell sites.

We have purchased substantially all of the equipment for our networks from Samsung Electronics, Ericsson–LG and Nokia Siemens Networks B.V. Most of the transmission lines we use, including virtually all of the lines linking switching stations, as well as a portion of the lines linking cell sites to switching stations, comprise optical fiber lines that we own and operate directly. However, we have not undertaken to install optical fiber lines to link every cell site and switching station. In places where we have not installed our own transmission lines, we have leased lines from KT and LG U+. We intend to increase the efficiency of our network utilization and provide optimal services by internalizing transmission lines.

We use a wireless network surveillance system. This system oversees the operation of cell sites and allows us to monitor our main equipment located throughout the country from one monitoring station. The automatic inspection and testing provided to the cell sites lets the system immediately rebalance to the most suitable setting, and the surveillance system provides for automatic dispatch of repair teams and quick recovery in emergency situations.

Marketing, Distribution and Customer Service

Marketing.    Our marketing strategy is focused on offering solutions tailored to the needs of our various customer segments, promoting our brand and leveraging our extensive distribution network. Our marketing plan includes a coordinated program of television, print, radio, outdoor signage, Internet and point-of-sale media promotions designed to relay a consistent message across all of our markets. We market our wireless products and services under the “T” brand, which signifies the centrality of “Telecommunications” and “Technology” to our business and also seeks to emphasize our commitment to providing “Top” quality, “Trustworthy” products and services to our customers.

We have implemented certain information technology improvements in connection with our marketing strategy, including customer management systems, as well as more effective information security controls. We believe these upgrades have enhanced our ability to process and utilize marketing- and subscriber-related data, which, in turn, has helped us to develop more effective and targeted marketing strategies. We currently operate a customer information system designed to provide us with an extensive customer database. Our customer information system includes a billing system that provides us with comprehensive account information for internal purposes and enables us to efficiently respond to customer requests. Our customers can also change their rate plans, verify the charges accrued on their accounts, receive their bills online and send text messages to our other subscribers through our website at www.tworld.co.kr and through our “T world” mobile application.

We strive to improve subscriber retention through our T Membership program, which is a membership service available to our wireless subscribers. Our T Membership program provides various membership benefits to its

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members such as discounts with our membership partners for dining, shopping, entertainment and travel, access to our online membership shopping mall and invitations to various promotional events. Although our competitors also have similar membership programs, we believe that our T Membership program has a competitive advantage over our competitors’ membership programs due to our large subscriber base and breadth of membership benefits.

Distribution.    We use a combination of an extensive network, including branch offices and stores, directly operated by us through our subsidiary, PS&Marketing, more than 3,500 authorized exclusive dealers and an extensive network of independent retailers in order to increase subscriber growth while reducing subscriber acquisition costs.

As part of our initiative to provide a differentiated customer service experience, we operate T Premium Stores that allow our potential and existing subscribers to experience certain of our services such as services that are available through our IoT solutions and platform services. As of December 31, 2018, we operated more than 440 T Premium Stores.

In addition, we operate an online distribution channel, “T World Direct,” through which subscribers can conveniently purchase wireless devices and subscribe to our services online. We also operate a dedicated online shop on 11st, our e-commerce marketplace. We intend to continue to develop our online distribution channel to leverage our offline distribution capabilities to provide convenience and additional value to our subscribers. For example, subscribers purchasing wireless devices through T World Direct can opt to pick up their devices at one of our offline stores.

Currently, authorized dealers are entitled to an initial commission for each new subscriber registered by the dealer, as well as an average ongoing commission calculated as a percentage of that subscriber’s monthly plan-based rate for the first four years. In order to strengthen our relationships with our exclusive dealers, we offer a dealer financing plan, pursuant to which we provide to each authorized dealer a loan of up to Won 4.0 billion with a repayment period of up to three years. As of December 31, 2018, we had an aggregate of Won 61.8 billion outstanding in loans to authorized dealers.

Customer Service.    We provide high-quality customer service directly through our two subsidiaries, Service Ace Co., Ltd. and Service Top Co., Ltd., rather than rely on outsourcing. Network O&S Co., Ltd. operates our switching stations and related transmission and power facilities and offers quality customer service primarily to our business customers. We have held the top position with respect to our telecommunications service and retail sales service in Korea’s leading three customer satisfaction indices, the National Customer Satisfaction Index, the Korean Customer Satisfaction Index and the Korean Standard Service Quality Index, for 22 years, 21 years and 19 years, respectively.

Fixed-line Telecommunication Services

We offer fixed-line telephone, broadband Internet and advanced media platform services (including IPTV and mobile OTT services) and business communications services through our fixed-line telecommunication services segment. Our fixed-line telecommunications services are provided by our subsidiaries, SK Broadband and SK Telink. The following table sets forth historical information about our subscriber base for our fixed-line telecommunication services for the periods indicated:

In 2018, 2017 and 2016, our fixed-line telecommunication services segment revenue was Won 2,932.6 billion, Won 2,724.2 billion and Won 2,651.2 billion, respectively, representing 17.4%, 15.5% and 15.5%, respectively, of our consolidated revenue.

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As part of our efforts to enhance our capabilities and increase our market share in the fixed-line business, in April 2019, we entered into an agreement with Tbroad, a leading cable television and other fixed-line telecommunication services provider in Korea, pursuant to which Tbroad will merge with and into SK Broadband. The completion of such transaction is subject to regulatory approvals and other closing conditions. Upon the completion of the merger, which is expected to occur by early 2020, we expect to own approximately 74.4% of SK Broadband’s total outstanding shares. In addition, SK Telecom signed a separate share purchase agreement with Tbroad Co., Ltd. to acquire a 55.0% equity interest in Tbroad Nowon.

Fixed-line Telephone Services

Our fixed-line telephone services comprise local, domestic long distance, international long distance and VoIP services. VoIP is a technology that transmits voice data through an Internet Protocol network. As of December 31, 2018, we had approximately 4.1 million fixed-line telephone subscribers (including subscribers to VoIP services of SK Broadband and SK Telink). Our fixed-line telephone services are primarily offered under the “B phone” brand name. SK Telink also provides affordable international calling services under the brand name “00700.”

Broadband Internet Access Services

Our broadband Internet access network covered more than 85% of households in Korea as of December 31, 2018. As of December 31, 2018, we had approximately 5.4 million broadband Internet access subscribers. We offer broadband Internet access products with various throughput speeds, including “Giga Internet,” which is up to 10 times faster than data transmission speeds on networks utilizing FTTH technology and allows for data transmission at a maximum speed of 1 Gbps.

Advanced Media Platform (including IPTV and Mobile OTT Services)

As part of our initiative to be the leading next-generation platform provider, we aim to provide an advanced media platform with various media content and service offerings.

We have offered video-on-demand services since 2006 and launched real-time IPTV services in 2009. We currently offer IPTV services under the brand name “B tv” with access to our standard 56 live high definition channels and to as many as 236 channels depending on the subscription service, as well as video-on-demand service providing a wide range of media content, including recent box office movie releases, popular U.S. and other foreign TV shows and various children’s TV programs. We also offer “B tv UHD,” which is an ultra-high definition IPTV service and has a resolution that is four times as high as the standard high definition broadcasting service in the IPTV industry. As of December 31, 2018, we had approximately 4.7 million IPTV subscribers. In January 2018, we launched B tv NUGU, which is an all-in-one set top box that incorporates NUGU voice recognition technology and can search for and play media content as well as connect to our Smart Home service through voice commands.

In January 2016, we launched “oksusu,” a mobile OTT service that provides subscribers access to a wide variety of media contents, including various television programs, movies and other video contents that can be downloaded to wireless devices. Oksusu subscribers have access to more than 100 live TV channels, a wide range of sports contents and popular U.S. and other foreign TV shows, among other contents. We are also collaborating with media content developers to provide original media content for our oksusu service. As of December 31, 2018, we had approximately 9.7 million subscribers to oksusu.

In April 2019, in furtherance of our efforts to enhance the competitiveness of our media business and to promote its future growth, we entered into an agreement with Content Alliance Platform, a joint venture among the three major terrestrial broadcasters in Korea that operates the mobile OTT service POOQ, pursuant to which we will transfer our oksusu business to Content Alliance Platform to pursue a combination of the two mobile OTT services and participate in a capital increase by Content Alliance Platform through a third-party allotment for a cash consideration of Won 90.0 billion.

We continue to expand the scope of our media services and content offerings to provide our subscribers with a vast library of high-quality content that can be accessed through our wireless networks and our fixed-line network.

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Business Communications Services

We offer other business communications services to our business customers, including corporations and government entities. Our business communications services include leased line solutions, Internet data center solutions and network solution services.

Our leased line solutions are exclusive lines that allow point-to-point connection for voice and data traffic between two or more geographically separate points. We hold a license to operate leased line services on a nationwide basis in Korea and also use international transmission lines to provide leased line services to other countries. Our leased line services enable high volumes of data to be transmitted swiftly and reliably. We also provide back-up storage for transmitted data. Through our Internet data center, we provide our business subscribers with server-based support including co-location, dedicated server hosting and cloud computing services. Our network solution service utilizes our network infrastructure and voice platform to provide 24-hour monitoring and control of our customers’ networks. Through this service, we conduct remote monitoring of our customers’ data and voice communications infrastructure and network and traffic conditions, and carry out preventive examinations and on-site visits.

T-commerce

We also operate an interactive television shopping (“T-commerce”) network, “SK stoa,” through our consolidated subsidiary SK stoa Co., Ltd. (“SK Stoa”), which offers a broad assortment of goods and services through pre-recorded television programming. The goods and services promoted on SK stoa’s T-commerce programming can be purchased through telephone orders or mobile application or directly through a virtual application appearing on the television screen using the viewer’s remote controller. In March 2019, SK Stoa launched “SK stoa ON,” which offers searchable shopping programming that is available to viewers at their convenience by utilizing video-on-demand capabilities. In April 2019, SK Stoa became a direct subsidiary of SK Telecom upon the transfer of SK Broadband’s 100% equity interest in SK Stoa to SK Telecom.

Rate Plans

For our residential customers, we offer both bundled rate plans for a combination of our fixed-line service offerings as well as individual rate plans for each separate service offering. Bundled rate plans are offered at a discount compared to subscribing to the same services through individual rate plans. Approximately 87% of subscribers to our fixed-line services subscribe to two or more of our services through our bundled rate plans. Bundled rate plans for a combination of fixed-line telephone, broadband Internet access and IPTV services range from Won 22,000 to Won 73,700 per month.

Our “Unlimited Home Phone” plan for subscribers to our fixed-line telephone service features unlimited domestic land-to-land voice minutes for a fixed rate and range from Won 7,700 to Won 11,550 per month depending on whether or not the subscriber opts for a contract and if so, the length of the contract period. We offer individual fixed-rate plans for our broadband Internet access service that range from Won 33,000 to Won 104,500 per month depending on the data throughput speed and existence and length of a contract. We offer individual fixed-rate plans for our IPTV service that range from Won 6,600 to Won 30,800 per month depending on the number of channels provided and existence and length of a contract. In addition, subscribers can purchase individual videos on demand or subscribe to certain paid content on a periodic basis.

With respect to our business communications services, we offer rates that are tailored to the specific needs of our business customers. We also charge certain installation fees and equipment rental fees as well as other ancillary fees with respect to certain of our fixed-line telecommunications services.

Marketing, Distribution and Customer Service

We focus on bringing our fixed-line telephone, broadband Internet and advanced media platform services (including IPTV and mobile OTT services) to residential users, and various business communications services to corporate users. We market our fixed-line telecommunications products and services under the “B” brand. Our “B” brand signifies the centrality of “Broadband” to our business and also seeks to emphasize our commitment to

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providing the “Best” quality products and services to our customers that go “Beyond” expectations, leading to a “Bravo” response. Our “B” brand also strengthens our shared identity with our wireless service’s “T” brand.

We currently outsource a significant portion of our retail sales force needs. We market our services and provide after-sales service support to customers through more than 70 customer centers and a network of more than 160 authorized exclusive dealers located throughout Korea. In addition, SK Telecom’s direct retail stores and authorized dealers for wireless telecommunications services also market our fixed-line telephone, broadband Internet and advanced media platform services (including IPTV and mobile OTT services), which we believe has contributed to the increase in the number of subscribers to such services. We have contracts with our customer centers to sell our services exclusively. These centers receive a commission for each service contract and installation contract secured. In addition, we pay these centers for the maintenance and repair work that they perform for our subscribers. Customer and service centers often enter into sub-contracts with smaller distribution outlets within their area to increase their sales coverage and engage in telemarketing efforts. Authorized dealers are entitled to an initial commission for each new subscriber registered by the dealer.

Sales to business subscribers are handled through our in-house sales group. Our sales teams focus on securing contracts with large commercial complexes, allowing us to install our remote terminals at their premises. After installation, sales teams direct their attention to individual business clients within these premises. Sales teams that have secured contracts with business clients remain the primary contacts for all aspects of the client’s needs, including further installation and customer and follow-up service.

E-Commerce Services

Our e-commerce services segment consists primarily of “11st,” our online marketplace business operated by Eleven Street, which was spun-off as our new consolidated subsidiary from SK Planet in September 2018. In connection with such spin-off, Eleven Street received a Won 500 billion equity investment in the form of redeemable convertible preferred shares from a group of financial investors led by H&Q Korea Partners, LLC, pursuant to which such financial investors held an 18.2% equity interest in Eleven Street as of December 31, 2018.

In 2018, 2017 and 2016, our e-commerce services segment revenue was Won 618.1 billion, Won 647.1 billion and Won 546.2 billion, respectively, representing 3.7%, 3.7% and 3.2%, respectively, of our consolidated revenue. Following the spin-off of Eleven Street from SK Planet, the marketing platform business operations of SK Planet, which were previously part of our e-commerce services segment in 2017 and 2016, were reclassified as part of our other businesses segment for 2018. See “— Other Businesses — Miscellaneous Businesses — Marketing Platform Business” below.

11st is an online open marketplace that offers a wide range of products through an online and mobile platform. Individual consumers can buy a vast array of products such as clothes and accessories, beauty products, groceries, baby products, books, office supplies, furniture, home goods, outdoor and sporting goods, appliances, electronics, travel packages, entertainment tickets and local deals for restaurants and other services from small- to large-sized retailers that operate “mini malls” on the 11st platform. Eleven Street also operates 11Pay, a convenient and secure payment service through which users can register their credit card to simplify payments for online and mobile purchases, including through 11st.

As of December 31, 2018, 11st was the leading commerce platform in terms of unique visitors, both on the basis of mobile version only and the combined basis of mobile and desktop versions, according to Nielsen Koreanclick. The mobile version of 11st is continuing to grow with an increase in the percentage of annual gross merchandise volume, which represents the total annual monetary value of customer purchases of goods and services, net of estimated refunds, derived from the mobile platform to 65% in 2018 from 61% in 2017 and 52% in 2016. We intend to continue our efforts to increase usage of the mobile version of 11st, enhance the convenience of our 11st mobile and web user interface and create synergies with our other products and services.

Other Businesses

We strive to continually diversify our products and services and develop new growth engines that we believe are complementary to our existing products and services, such as our portal service and other miscellaneous

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businesses, which we include in our other businesses segment. In 2018, 2017 and 2016, our other businesses segment revenue was Won 944.4 billion, Won 886.6 billion and Won 889.5 billion, respectively, representing 5.6%, 5.1% and 5.2%, respectively, of our consolidated revenue.

Portal Service

We offer a portal service under our “Nate” brand name through SK Communications. Nate can be accessed through its website, www.nate.com, or through its mobile application. Nate offers a wide variety of content and services, including Nate Search, an Internet search engine, Nate News, which provides a library of articles about current events, sports, entertainment and culture, Nate Pann, a user-generated content service as well as access to free e-mail accounts through Nate Mail.

Miscellaneous Businesses

Marketing Platform Business.    We provide marketing platform services through SK Planet, which include the following:

Security.    Our security business consists primarily of our physical security services provided by ADT Caps and our information security services provided by SK Infosec. We acquired ADT Caps in October 2018 by acquiring a 55.0% interest in LSH, which owns 100% of ADT Caps, for Won 696.7 billion. In December 2018, we merged NSOK Co., Ltd. (“NSOK”), which was our consolidated subsidiary and a provider of residential and small business electronic security and other related alarm monitoring services, with and into ADT CAPS Co., Ltd.

ADT Caps offers its flagship unmanned monitoring and dispatch service called the “Central Monitoring Service,” as well as access control, video surveillance and other integrated security services. Following our acquisition of ADT Caps, we have explored and continue to explore synergies between our security business and other key business segments. For example, we launched “T Safe Security,” a video surveillance and security guard dispatch service offered through the distribution channels for our wireless services, in October 2018. In addition, we also introduced our bundle-based discounted rate plans “T&Caps” in November 2018 and “B&Caps” in January 2019, which bundle our wireless service and broadband Internet service, respectively, with ADT Caps’ security service.

We also offer information security solutions through our subsidiary SK Infosec. We acquired SK Infosec from SK Holdings, our largest shareholder, in a share exchange transaction in December 2018, pursuant to which we transferred 1,260,668 treasury shares with an aggregate book value of Won 281.2 billion to SK Holdings in exchange for all of the issued and outstanding common shares of SK Infosec. SK Infosec provides information security consulting services, managed security services as well as cyber threat intelligence solutions.

Furthermore, in order to strengthen our data security capabilities in light of expected increases in data transmission by wireless service subscribers and users of our IoT solutions through our 5G network, we increased our equity interest in id Quantique, a leading provider of quantum cryptography solutions for data security based in Switzerland, to 65.6% during 2018.

Others.    We offer high-end audio devices under the brand name “Astell&Kern” that are manufactured by our subsidiary, Dreamus. In 2016, two of Dreamus’ audio devices were selected as CES Innovation Awards Honorees in the Portable Media Player and Accessories category and High Performance Home Audio/Video category, respectively, and in 2017, an Dreamus audio device was selected as an CES Innovation Awards Honoree in the Accessories category. In 2017 and 2018, we acquired additional equity interests in Dreamus for Won 25.0 billion and Won 65.0 billion, respectively, and as of December 31, 2018, we had a 52.6% equity interest in Dreamus.

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In December 2018, we launched a new personalized music platform called “FLO,” which provides customized music recommendations and user interfaces by analyzing individual user preferences with our AI technology.

We also operate a mobile application marketplace, “One Store” in collaboration with KT, LG U+ and NAVER Corporation. Through this joint collaboration, we expect to increase the competitiveness of One Store to compete with Google Playstore, the leading mobile application marketplace in Korea. As of December 31, 2018, we held a 65.5% interest in One Store.

Interconnection

Our wireless and fixed-line networks interconnect with the public switched telephone networks operated by KT and SK Broadband and, through their networks, with the international gateways of KT and LG U+, as well as the networks of the other wireless telecommunications service providers in Korea. These connections enable our subscribers to make and receive calls from telephones outside our networks. Under Korean law, service providers are required to permit other service providers to interconnect to their networks. If a new service provider desires interconnection with the networks of an existing service provider but the parties are unable to reach an agreement within 90 days, the new service provider can appeal to the KCC.

Domestic Calls

Guidelines issued by the MSIT require that all interconnection charges levied by a regulated carrier take into account (i) the actual costs to that carrier of carrying a call or (ii) imputed costs. The MSIT determines interconnection rates applicable to each carrier based on changes in traffic volume, taking into account other factors such as research results, competition and trends in technology development.

Wireless-to-Fixed-line.    According to our interconnection arrangement with KT, for a call from our wireless network to KT’s fixed-line network, we collect the usage rate from our wireless subscriber and in turn pay KT the interconnection charges. Similarly, KT pays interconnection charges to SK Broadband for a call from KT’s wireless network to SK Broadband’s fixed-line network. The interconnection rate applicable to both KT and SK Broadband was Won 9.99 per minute, Won 10.86 per minute and Won 11.98 per minute for 2018, 2017 and 2016, respectively.

Fixed-line-to-Wireless.    The MSIT determines interconnection arrangements for calls from a fixed-line network to a wireless network. For a call initiated by a fixed-line user to one of our wireless subscribers, the fixed-line network operator collects our usage fee from the fixed-line user and remits to us an interconnection charge. Interconnection with KT accounts for substantially all of our fixed-line-to-wireless interconnection revenue and expenses.

The interconnection rates paid by fixed-line network service providers to each wireless network service provider are set out below. Beginning in 2017, a single interconnection rate applies to all wireless telecommunications service providers, which has eliminated the cost benefit that KT and LG U+ had historically derived from the higher interconnection rates they had received.

Wireless-to-Wireless.     Interconnection charges also apply to calls between wireless telephone networks in Korea. Under these arrangements, the operator originating the call pays an interconnection charge to the operator terminating the call. The applicable interconnection rate is the same as the fixed-line-to-wireless interconnection rate set out in the table above.

Our revenues from the wireless-to-wireless charge were Won 498.5 billion in 2018, Won 505.1 billion in 2017 and Won 540.3 billion in 2016. Our expenses from these charges were Won 494.2 billion in 2018, Won 512.2 billion in 2017 and Won 548.1 billion in 2016. The charges above were agreed among the parties involved and confirmed by the KCC.

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International Calls and International Roaming Arrangements

With respect to international calls, if a call is initiated by our wireless subscribers, we bill the wireless subscriber for the international charges of KT, LG U+ or SK Broadband, and we receive interconnection charges from such operators. If an international call is received by our subscriber, KT, LG U+ or SK Broadband pays interconnection charges to us based on our imputed costs.

To complement the services we provide to our subscribers in Korea, we offer international voice and data roaming services. We charge our subscribers usage fees for global roaming service and, in turn, pay foreign wireless network operators fees for the corresponding usage of their network. For a more detailed discussion of our global roaming services, see “— Wireless Services” above.

Competition

We operate in highly saturated and competitive markets, and we believe that our subscriber growth is affected by many factors, including the expansion and technical enhancement of our networks, the development and deployment of new technologies, the effectiveness of our marketing and distribution strategy, the quality of our customer service, the introduction of new products and services, competitive pricing of our rate plans, new market entrants and regulatory changes.

Historically, there has been considerable consolidation in the telecommunications industry, resulting in the current competitive landscape comprising three mobile and fixed network operators in the Korean market, KT, LG U+ and us. Each of our competitors has substantial financial, technical, marketing and other resources to respond to our business offerings.

The following table shows the market share information, based on number of subscribers, as of December 31, 2018, for the following markets.

Cellular Services

As of December 31, 2018, we had 30.9 million subscribers, representing a market share of approximately 47.2%, including MVNO subscribers leasing our networks. As of December 31, 2018, KT and LG U+ had 20.6 million and 13.8 million subscribers, respectively, representing approximately 31.6% and 21.2%, respectively, of the total number of wireless subscribers in Korea on such date, each including MVNO subscribers leasing its networks. As of December 31, 2018, we had 24.8 million LTE subscribers and KT and LG U+ had 17.0 million and 13.4 million LTE subscribers, respectively, each including MVNO subscribers leasing its networks.

In 2018, we had 5.2 million activations and 4.5 million deactivations. For 2018, our monthly churn rate ranged from 1.2% to 1.3%, with an average monthly churn rate of 1.2% for 2018, which decreased from 1.5% for 2017. In 2018, we gained 38.3% of the total number of new wireless subscribers and subscribers that migrated to a different wireless telecommunications service provider, compared to KT with 33.3% and LG U+ with 28.4%.

We also compete for subscriber activations with MVNOs, including MVNOs that lease our networks. MVNOs generally provide rate plans that are relatively cheaper than similar rate plans of the wireless network providers

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from which they lease their networks, including us. To date, thirteen MVNOs have commenced providing wireless telecommunications services using the networks leased from us. As of December 31, 2018, MVNOs had a combined market share of 12.2%, of which MVNOs leasing our networks represented 5.4%, MVNOs leasing KT’s networks represented 5.7% and MVNOs leasing LG U+’s networks represented 1.2%.

In addition, other companies may enter the wireless network services market. New entries in such market have historically required obtaining requisite licenses from the MSIT. However, pursuant to an amendment to the Telecommunications Business Act, which will become effective in June 2019, companies meeting certain regulatory criteria may become a network service provider by registering with the MSIT without a separate license requirement, which may have the effect of encouraging new entries into the Korean wireless network services market in the future. For a description of the risks associated with the competitive environment in which we operate, see “Item 3.D. Risk Factors — Risks Relating to Our Business — Competition may reduce our market share and harm our results of operations and financial condition.”

Historically, competition in the wireless telecommunications business had caused us to significantly increase our marketing and advertising expenses from time to time depending on the prevailing competitive landscape, with our marketing expenses as a percentage of SK Telecom’s revenue, on a separate basis, reaching a peak of 28.2% in 2012. Such percentage was 23.9% in 2016, 25.0% in 2017 and 24.5% in 2018. We attribute such stabilization to the maturity of the LTE market and the implementation of the MDDIA, which prohibits wireless telecommunications service providers from unfairly providing discriminatory subsidies based on certain criteria and from providing subsidies exceeding a maximum limit established by the KCC for the purchase of mobile phone models that were launched within the last 15 months, among other restrictions and requirements. However, the prohibition from providing handset subsidies exceeding the amount set by the KCC expired in September 2017 pursuant to the expiration of the three-year effective period of the relevant provision of the MDDIA. For a more detailed discussion of the MDDIA, see “— Law and Regulation — Rate Regulation” below.

We face competition from KT and LG U+ as well as other platform service providers in our other cellular service businesses. For example, our Smart Home service competes with KT’s Giga IoT Home service and LG U+’s IoT@Home service.

Fixed-Line Telecommunication Services

Our fixed-line telephone service competes with KT and LG U+ as well as providers of other VoIP services. As of December 31, 2018, our market share of the fixed-line telephone and VoIP service market was 16.0% (including the services provided by SK Broadband and SK Telink) in terms of number of subscribers compared to KT with 57.7% and LG U+ with 17.4%.

We are the second largest provider of broadband Internet access services in Korea in terms of both revenue and subscribers, and our network covered more than 80% of households in Korea as of December 31, 2018. As of December 31, 2018, our market share of the broadband Internet market was 25.4% in terms of number of subscribers compared to KT with 41.0% and LG U+ with 18.9%.

Our IPTV service competes with other providers of such pay TV services, including KT, LG U+ and cable companies. As of December 31, 2018, our market share of the pay TV market (which includes IPTV, cable TV and satellite TV) was 14.1% compared to KT with 23.3% and LG U+ with 11.9% and the collective market share of other pay TV providers of 50.7%. With respect to our mobile OTT business, we face competition from similar services provided by KT and LG U+. We also face increasing competition from global media streaming service providers such as Amazon Video and Netflix, which launched its services in Korea in January 2016.

Recently, the Korean fixed-line telecommunications industry has been going through significant consolidation involving major cable television service providers. In January 2019, LG U+ announced its plan to acquire a majority equity stake in CJ Hello, which is one of the largest cable television and other fixed-line telecommunication services providers in Korea. In April 2019, SK Broadband entered into an agreement with Tbroad, a leading cable television and other fixed-line telecommunication services provider in Korea with consolidated total assets of Won 1,192.3 billion and consolidated total revenue of Won 684.1 billion as of and for the year ended December 31, 2018, pursuant to which Tbroad will merge with and into SK Broadband. Upon the completion of such merger, which is

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expected to occur by early 2020, we expect to own approximately 74.4% of SK Broadband’s equity interest. In addition, SK Telecom signed a separate share purchase agreement with Tbroad Co., Ltd. to acquire a 55.0% equity interest in Tbroad Nowon for a purchase price of Won 10.4 billion. While the completion of each of these transactions is currently pending, successful completion of such transactions, as well as further consolidation in the fixed-line telecommunications industry, may result in increased competition, as the entities emerging from such consolidation and other remaining players in the industry may actively pursue expanding or protecting their respective market shares.

Furthermore, the Government has historically enforced regulations on cable TV and IPTV service providers that prohibited them from having a market share of more than one-third of the total number of subscribers in the relevant pay TV market on each of their respective platforms. In June 2015, the Government amended the regulation to impose the same limit on the market share of the entire pay TV market, including satellite TV service providers as well. Such amended regulation, however, expired in June 2018, which has led to the speculation that KT, currently the dominant market player in both the IPTV and satellite TV markets, may further increase its market share by acquiring other players in the pay TV market. While the expiration of such regulation has prompted the submission of a number of bills in the National Assembly to extend its application, it is uncertain whether such bill will be passed.

E-Commerce Services

The e-commerce industry is evolving rapidly and is intensely competitive, and we face a broad array of competitors domestically and increasingly, internationally. Our marketplace business, 11st, faces intense competition from various e-commerce providers, including online open marketplaces such as Gmarket, Auction and Interpark and online social commerce operators such as Coupang, Ticket Monster and Wemakeprice. We also face competition from traditional retailers with online and mobile shopping portals such as SSG.com and Lotte.com, home shopping providers with online and mobile shopping portals such as CJ Mall by CJ O Shopping, GS Shop by GS Homeshopping and Hyundai Hmall by Hyundai Homeshopping, and various online marketplaces for specific consumer segments or product groups.

Other Investments and Relationships

We have investments in several other businesses and companies and have entered into various business arrangements with other companies. Our principal investments fall into the following categories:

SK Hynix

As of December 31, 2018, we held a 20.1% equity interest in SK Hynix, one of the world’s largest memory-chip makers by revenue. SK Hynix designs, manufactures and sells advanced memory semiconductor products, including DRAM and NAND flash products, used in various electronic devices. SK Hynix operates four wafer fabrication facilities in Korea and China.

As of December 31, 2018, the fair value of our holding in SK Hynix was Won 8,839.1 billion. We received dividend payments of Won 146.1 billion in 2018, Won 87.7 billion in 2017 and Won 73.1 billion in 2016 related to such shareholding. In 2018, 2017 and 2016, SK Hynix and its subsidiaries, on a consolidated basis, reported revenues of Won 40,445.1 billion, Won 30,109.4 billion and Won 17,198.0 billion, respectively, profit before income tax of Won 21,341.0 billion, Won 13,439.6 billion and Won 3,216.5 billion, respectively, and profit for the year of Won 15,540.0 billion, Won 10,642.2 billion and Won 2,960.5 billion, respectively. The increase in SK Hynix’s revenues in 2018 was primarily due to the continued increases in the demand for and average selling prices of DRAM and NAND flash products. As of December 31, 2018, 2017 and 2016, SK Hynix and its subsidiaries, on a consolidated basis, reported total assets of Won 63,658.3 billion, Won 45,418.5 billion and Won 32,216.0 billion, respectively, and total equity of Won 46,852.3 billion, Won 33,820.9 billion and Won 24,023.5 billion, respectively. For a more detailed discussion of the risks relating to our shareholding in SK Hynix, see “Item 3.D. Risk Factors — Risks Relating to Our Business — Declines in the market value of our equity holdings in SK Hynix and the results of operations of SK Hynix could have a material adverse effect on the market price of our common shares and ADSs as well as our results of operation.”

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KEB HanaCard

In February 2010, we purchased shares newly issued by Hana SK Card Co., Ltd. (which was subsequently merged into KEB Card Co., Ltd. and renamed KEB HanaCard Co., Ltd. (“KEB HanaCard”) in November 2014), a credit card services provider, for a total purchase price of Won 400.0 billion. As of December 31, 2018, we held 15.0% of the total outstanding shares of KEB HanaCard. KEB HanaCard offers certain credit card products that provide for discounts on some of our wireless network services and integrate T Membership benefits, among other features.

Law and Regulation

Overview

Korea’s telecommunications industry is subject to comprehensive regulation by the MSIT, which is responsible for information and telecommunications policies. The MSIT regulates and supervises a broad range of communications issues, including:

The MSIT is charged with regulating information and telecommunications and the KCC is charged with regulating the public interest aspects of and fairness in broadcasting.

Telecommunications service providers are currently classified into three categories: network service providers, value-added service providers, and specific service providers. We are classified as a network service provider because we provide telecommunications services with our own telecommunications networks and related facilities. As a network service provider, we are currently required to obtain a license from the MSIT for the services we provide. However, an amendment to the Telecommunications Business Act, pursuant to which companies meeting certain regulatory criteria may become a network service provider without a separate license requirement and the category of “specific service providers” will be merged into the category of “network service providers,” will become effective in June 2019. Our licenses permit us to provide cellular services, third generation wireless telecommunications services using WCDMA and WiBro technologies, fourth generation wireless telecommunications services using LTE technology and fifth generation wireless telecommunication services using 5G technology.

The MSIT may revoke our licenses or suspend any of our businesses if we fail to comply with its rules, regulations and corrective orders, including the rules restricting beneficial ownership and control and corrective orders issued in connection with any violation of rules restricting beneficial ownership and control or any violation of the conditions of our licenses. Alternatively, in lieu of suspension of our business, the KCC may levy a monetary penalty of up to 3.0% of the average of our annual revenue for the preceding three fiscal years. A network service provider that wants to cease its business or dissolve must notify its users 60 days prior to the scheduled date of cessation or dissolution and obtain MSIT approval.

In the past, the Government has stated that its policy was to promote competition in the Korean telecommunications market through measures designed to prevent the dominant service provider in any such market from exercising its market power in such a way as to prevent the emergence and development of viable competitors. While all network service providers are subject to MSIT regulation, we are subject to increased regulation because of our position as the dominant wireless telecommunications services provider in Korea.

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Competition Regulation

The KCC is charged with ensuring that network service providers engage in fair competition and has broad powers to carry out this goal. If a network service provider is found to be in violation of the fair competition requirement, the KCC may take corrective measures it deems necessary, including, but not limited to, prohibiting further violations, requiring amendments to the articles of incorporation or to service contracts with customers, requiring the execution or performance of, or amendments to, interconnection agreements with other network service providers and prohibiting advertisements to solicit new subscribers. The KCC is required to consult with the Minister of the MSIT before it takes certain corrective measures.

In addition, we qualify as a “market-dominating business entity” under the Fair Trade Act. Accordingly, we are prohibited from engaging in any act of abusing our position as a market-dominating entity, such as unreasonably determining, maintaining or altering service rates, unreasonably controlling the rendering of services, unreasonably interfering with business activities of other business entities, hindering unfairly the entry of newcomers or substantially restricting competition to the detriment of the interests of consumers.

Because we are a member company of the SK Group, which is a large business group as designated by the FTC, we are subject to the following restrictions under the Fair Trade Act:

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Rate Regulation

Network service providers whose sales proceeds exceed the amount prescribed by law must report to the MSIT the rates and contractual terms for each type of service they provide. However, as the dominant network service provider for specific services (based on having the largest market share in terms of number of subscribers and meeting certain revenue thresholds), we must obtain prior approval of the MSIT on our rates and terms of service; provided, however, that such pre-approval of the MSIT is not required, if we are planning to reduce the rates for any type of services that we provide under the MSIT-approved contractual terms. The MSIT’s policy is to approve rates if they are appropriate, fair and reasonable (that is, if the rates have been reasonably calculated, considering supply costs, profits, classification of costs and profits for each service, cost savings through changes in the way services are provided and the influence on fair competition, among others). The MSIT may order changes in the submitted rates if it deems the rates to be significantly unreasonable or against public policy. Multiple bills have been proposed to the National Assembly to change the approval requirement to a simple reporting requirement, which is the requirement for our competitors. However, there is no assurance as to which of these bills, if any, will be passed.

Furthermore, in 2007, the Government announced a “road map” highlighting revisions in regulations to promote deregulation of the telecommunications industry. In accordance with the road map and pursuant to the Combined Sales Regulation, promulgated in May 2007, telecommunications service providers are now permitted to bundle their services, such as wireless data transmission service, wireless voice transmission service, broadband Internet access service, fixed-line telephone service and IPTV service, at a discounted rate; provided, however, that we and KT, as market-dominating business entities under the Telecommunications Business Act, allow other competitors to employ the services provided by us and KT, respectively, so that such competitors can provide similar discounted package services. In September 2007, the regulations and provisions under the Telecommunications Business Act were amended to permit licensed transmission service providers to offer local, domestic long-distance and international telephone services, as well as broadband Internet access and Internet phone services, without additional business licenses.

Moreover, an MVNO system has been adopted and is in effect until its expiration on September 22, 2019 under the amended Telecommunications Business Act, which became effective on March 14, 2017. Under this system, the MSIT may designate and obligate certain wireless telecommunications services providers to allow an MVNO, at such MVNO’s request, to use their telecommunication network facilities at a rate mutually agreed upon that complies with the standards set by the MSIT. We were designated as the only wireless telecommunications services provider obligated to allow the other wireless telecommunications services provider to use our telecommunications network facilities. To date, thirteen MVNOs have commenced providing wireless telecommunications services using the networks leased from us.

On October 1, 2014, the MDDIA, enacted for the purpose of establishing a transparent and fair mobile distribution practice, became effective. The MDDIA limits the amount of subsidies a wireless telecommunications service provider can provide to subscribers in order to prevent excessive competition among wireless telecommunications service providers. Pursuant to the MDDIA, wireless telecommunications service providers are prohibited from (i) unfairly providing discriminatory subsidies based on criteria such as type of subscription, subscription plan and characteristics of the subscriber and (ii) entering into a separate agreement with subscribers imposing obligations to use a specific subscription plan as a condition for providing subsidies. The MDDIA also prohibited providing subsidies exceeding a maximum limit established by the KCC for the purchase of mobile phone models that were launched within the last 15 months, which prohibition expired in September 2017. See “Item 5.A. Operating Results — Overview — New Rate Regulations.”

In addition, under the MDDIA, wireless telecommunications service providers are obliged to provide certain benefits, such as discounted rates, to subscribers who subscribe to their service without receiving subsidies. In June 2017, the State Affairs Planning Advisory Committee of Korea announced that it would encourage wireless telecommunications service providers, including us, to increase the applicable discount rate offered to subscribers from 20% to 25%, which we adopted in September 2017, and to offer additional discounts to low income customers, including those on government welfare programs and senior citizen recipients of the basic pension, which we implemented in December 2017 and July 2018, respectively. We cannot provide assurance that we will not provide other rate discounts in the future to comply with the Government’s public policy guidelines or suggestions.

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Interconnection

Dominant network service providers such as ourselves that own essential infrastructure facilities or possess a certain market share are required to provide interconnection of their telecommunications network facilities to other service providers upon request. The MSIT sets and announces the standards for determining the scope, procedures, compensation and other terms and conditions of such provision, interconnection or co-use. We have entered into interconnection agreements with KT, LG U+ and other network service providers permitting these entities to interconnect with our network. We expect that we will be required to enter into additional agreements with new operators as the MSIT grants permits to additional telecommunications service providers.

Frequency Allocation

The MSIT has the discretion to allocate and adjust the frequency bandwidths for each type of service and may auction off the rights to certain frequency bandwidths. Upon allocation of new frequency bandwidths or adjustment of frequency bandwidths, the MSIT is required to give a public notice. The MSIT also regulates the frequency to be used by each radio station, including the transmission frequency used by equipment in our cell sites. All of our frequency allocations are for a definite term. We pay fees to the MSIT for our frequency usage that are determined based upon our number of subscribers, frequency usage by our networks and other factors. For 2018, 2017 and 2016, the fee amounted to Won 151.7 billion, Won 150.3 billion and Won 186.8 billion, respectively.

We currently use 10 MHz of bandwidth in the 800 MHz spectrum for our CDMA services, 10 MHz of bandwidth in the 2.1 GHz spectrum for our WCDMA services, 30 MHz of bandwidth in the 2.1 GHz spectrum, 20 MHz of bandwidth in the 800 MHz spectrum, 35 MHz of bandwidth in the 1.8 GHz spectrum and 60 MHz of bandwidth in the 2.6 GHz spectrum for our LTE services, as well as 100 MHz of bandwidth in the 3.5 GHz spectrum for our 5G services. We also plan to use 800 MHz of bandwidth in the 28 GHz spectrum for our 5G services in the future. For more information regarding the license fees for the various bandwidths that we use, see “Item 5.B. Liquidity and Capital Resources — Capital Requirements — Capital Expenditures” and note 16 of the notes to our consolidated financial statements.

For risks relating to the maintenance of adequate bandwidth capacity, see “Item 3.D. Risk Factors — Risks Relating to Our Business — Our business and results of operations may be adversely affected if we fail to acquire adequate additional spectrum or use our bandwidth efficiently to accommodate subscriber growth and subscriber usage.”

Mandatory Contributions and Obligations

All telecommunications service providers other than value-added service providers and regional paging service providers or any telecommunications service providers whose net annual revenue is less than an amount determined by the MSIT (currently set at Won 30.0 billion) are required to provide “universal” telecommunications services including local telephone services, local public telephone services, telecommunications services for remote islands and wireless communication services for ships and telephone services for handicapped and low-income citizens, or contribute toward the supply of such universal services. The MSIT designates universal services and the service provider who is required to provide each service. Currently, under the MSIT guidelines, we are required to offer free subscription and a discount of between 30.0% to 50.0% of our monthly fee for wireless telecommunications services to handicapped and low-income citizens.

In addition to such universal services for handicapped and low-income citizens, we are also required to make certain annual monetary contributions to compensate for other service providers’ costs for the universal services. The size of a service provider’s contribution is based on its net annual revenue for the previous year (calculated pursuant to the MSIT guidelines, which differ from our accounting practices). We paid such contributions amounting to Won 16.7 billion, Won 13.6 billion and Won 21.1 billion in 2018, 2017 and 2016, respectively. As a wireless telecommunications services provider, we are not considered a provider of universal telecommunications services and do not receive funds for providing universal service. Other network service providers that do provide universal services make all or a portion of their “contribution” in the form of expenses related to the universal services they provide.

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Foreign Ownership and Investment Restrictions and Requirements

Because we are a network service provider, and the exception for the foreign shareholding limit under the amended Telecommunications Business Act, which became effective on August 13, 2013, does not apply to us, foreign governments, individuals, and entities (including Korean entities that are deemed foreigners, as discussed below) are prohibited from owning more than 49.0% of our voting stock. Korean entities whose largest shareholder is a foreign government or a foreigner (together with any of its related parties) that owns 15.0% or more of the outstanding voting stock of such Korean entities are also deemed foreigners. If this 49.0% ownership limitation is violated, certain of our foreign shareholders will not be permitted to exercise voting rights in excess of the limitation, and the MSIT may require other corrective action.

As of December 31, 2018, SK Holdings owned 21,624,120 shares of our common stock, or 26.8% of our issued shares. As of December 31, 2018, the two largest foreign shareholders of SK Holdings each held a 3.5% stake therein. If such foreign shareholders increase their shareholdings in SK Holdings to 15% or more and any such foreign shareholder constitutes the largest shareholder of SK Holdings, SK Holdings will be considered a foreign shareholder, and its shareholding in us would be included in the calculation of our aggregate foreign shareholding. If SK Holdings’ shareholding in us is included in the calculation of our aggregate foreign shareholding, then our aggregate foreign shareholding, assuming the foreign ownership level as of December 31, 2018 (which we believe was 41.8%), would reach 68.6%, exceeding the 49.0% ceiling on foreign shareholding.

If our aggregate foreign shareholding limit is exceeded, the MSIT may issue a corrective order to us, the breaching shareholder (including SK Holdings if the breach is caused by an increase in foreign ownership of SK Holdings) and the foreign shareholder which owns in the aggregate 15.0% or more of SK Holdings. Furthermore, SK Holdings will be prohibited from exercising its voting rights with respect to the shares held in excess of the 49.0% ceiling, which may result in a change in control of us. In addition, the MSIT will be prohibited from granting us licenses or permits necessary for entering into new telecommunications businesses until our aggregate foreign shareholding is reduced to below 49.0%. If a corrective order is issued to us by the MSIT arising from the violation of the foregoing foreign ownership limit, and we do not comply within the prescribed period under such corrective order, the MSIT may:

Additionally, the Telecommunications Business Act also authorizes the MSIT to assess monetary penalties of up to 0.3% of the purchase price of the shares for each day the corrective order is not complied with, as well as a prison term of up to one year or a penalty of Won 50 million. See “Item 3.D. Risk Factors — Risks Relating to Our Business — If SK Holdings causes us to breach the foreign ownership limitations on our common shares, we may experience a change of control.”

We are required under the Foreign Exchange Transaction Act to file a report with a designated foreign exchange bank or with the MOEF, in connection with any issue of foreign currency denominated securities by us in foreign countries. Issuances of US$30 million or less require the filing of a report with a designated foreign exchange bank, and issuances that are over US$30 million in the aggregate within one year from the filing of a report with a designated foreign exchange bank require the filing of a report with the MOEF.

The Telecommunications Business Act provides for the creation of a Public Interest Review Committee under the MSIT to review investments in or changes in the control of network service providers. The following events would be subject to review by the Public Interest Review Committee:

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If the Public Interest Review Committee determines that any of the foregoing transactions or events would be detrimental to the public interest, then the MSIT may issue orders to stop the transaction, amend any agreements, suspend voting rights, or divest the shares of the relevant network service provider. Additionally, if a dominant network service provider (which would currently include us and KT), together with its specially related persons (as defined under the FSCMA), holds more than 5.0% of the equity of another dominant network service provider, the voting rights on the shares held in excess of the 5.0% limit may not be exercised.

Patents and Licensed Technology

Access to the latest relevant technology is critical to our ability to offer the most advanced wireless telecommunications services and to design and manufacture competitive products. In addition to active internal and external research and development efforts as described in “Item 5.C. Research and Development, Patents and Licenses, etc.,” our success depends in part on our ability to obtain patents, licenses and other intellectual property rights covering our products. We own numerous patents and trademarks worldwide, and have applications for patents pending in many countries. Our patents are mainly related to LTE and 5G technology and wireless Internet applications. We have also acquired a number of patents related to WCDMA and CDMA technologies. There are no licensed patents that are material to our business.

We are not currently involved in any material litigation regarding patent infringement. For a description of the risks associated with our reliance on intellectual property, see “Item 3.D. Risk Factors — Risks Relating to Our Business — Our business relies on technology developed by us, and our business will suffer if we are unable to protect our proprietary rights.”

Seasonality of the Business

Our business is not affected by seasonality.

Organizational Structure

We are a member of the SK Group, based on the definition of “group” under the Fair Trade Act. As of December 31, 2018, SK Group members owned in aggregate 26.8% of the shares of our issued common stock. The SK Group is a diversified group of companies incorporated in Korea with interests in, among other things, telecommunications, trading, energy, chemicals, engineering and leisure industries.

Significant Subsidiaries

For information regarding our subsidiaries, see note 1(2) of the notes to our consolidated financial statements.

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The following table sets forth certain information concerning our principal properties as of December 31, 2018:

Our registered office and corporate headquarters, of which we have full ownership, are located at SK T-Tower, 65, Eulji-ro, Jung-gu, Seoul 04539, Korea, which occupy a total land area of approximately 64,515 square feet. In addition, we own or lease various locations for cell sites and switching equipment. We do not anticipate that we will encounter material difficulties in meeting our future needs for any existing or prospective leased space for our cell sites. See “Item 4.B. Business Overview — Cellular Services — Network Infrastructure.”

We maintain a range of insurance policies to cover our assets and employees, including our directors and officers. We are insured against business interruption, fire, lightning, flooding, theft, vandalism, public liability and certain other risks that may affect our assets and employees. We believe that the types and amounts of our insurance coverage are in accordance with general business practices in Korea.

We do not have any unresolved comments from the SEC staff regarding our periodic reports under the Exchange Act.

You should read the following discussion together with our consolidated financial statements and the related notes thereto which appear elsewhere in this annual report. We prepare our consolidated financial statements in accordance with IFRS as issued by the IASB. In addition, you should read carefully the section titled “— Critical Accounting Policies, Estimates and Judgments” as well as note 4 of the notes to our consolidated financial statements which provide summaries of certain critical accounting policies that require our management to make difficult, complex or subjective judgments relating to matters which are highly uncertain and that may have a material impact on our financial conditions and results of operations.

Overview

Our operations are reported in four segments: (1) cellular services, which include wireless voice and data transmission services, sales of wireless devices, IoT solutions and platform services, (2) fixed-line

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telecommunication services, which include fixed-line telephone services, broadband Internet services, advanced media platform services (including IPTV and mobile OTT services) and business communications services, (3) e-commerce services, which include our open marketplace platform, 11st, and related ancillary services, and (4) other businesses, which include our portal service, marketing platform business, physical and information security businesses and certain other miscellaneous businesses that do not meet the quantitative thresholds to be separately considered reportable segments.

In our cellular services segment, we earn revenue principally from our wireless voice and data transmission services through monthly plan-based fees, usage charges for outgoing voice calls, usage charges for wireless data services and value-added service fees paid by our wireless subscribers as well as interconnection fees paid to us by other telecommunications operators for use of our wireless network by their customers and subscribers. We also derive revenue from sales of wireless devices by PS&Marketing. Other sources of revenue include revenue from our IoT solutions and platform services, including AI solutions, as well as other miscellaneous cellular services.

In our fixed-line telecommunication services segment, we earn revenue principally from our fixed-line telephone services and broadband Internet services and advanced media platform services (including IPTV and mobile OTT services) through monthly plan-based fees and usage charges as well as interconnection fees paid to us by other telecommunications operators for use of our fixed-line network by their customers and subscribers. In addition, we derive revenue from international calling services and our business communications services through customized fee arrangements with our business customers.

In our e-commerce services segment, we derive revenue from our subsidiary Eleven Street, which was spun-off as our new consolidated subsidiary from SK Planet in September 2018. Eleven Street generates revenue principally through third-party seller fees earned (including commissions) for transactions in which it acts as a selling agent to the “mini malls” on 11st, its online open marketplace platform, as well as advertising revenue and other commerce solutions from 11st. Following the spin-off of Eleven Street from SK Planet, the remaining marketing platform business operations of SK Planet, which were previously part of our e-commerce services segment in the years ended December 31, 2017 and 2016, were reclassified as part of our other businesses segment for the year ended December 31, 2018. As a result, the breakdown of our results of operations by operating segment for the years ended December 31, 2017 and 2016 in our consolidated audited financial statements have been recast to retroactively apply such change in segmentation.

In our others segment, we earn revenue from our “Nate” portal service operated by our subsidiary, SK Communications, and miscellaneous other businesses, including the marketing platform business of SK Planet, our physical and information security businesses through ADT Caps (which we acquired in October 2018 and subsequently merged with our former subsidiary NSOK) and SK Infosec (which we acquired in December 2018) and certain other businesses.

Our cellular service revenue and fixed-line telecommunications service revenue depend principally upon the number of our subscribers, the rates we charge for our services, the frequency and volume of subscriber usage of our services and the terms of our interconnection with other telecommunications operators. Our e-commerce service revenue depends principally upon the gross merchandise volume, which is the total monetary value of customer purchases of goods and services, net of estimated refunds, of 11st and the number of merchants that utilize 11st to advertise and promote their products and services and the extent of such advertisement and promotion.

Among other factors, management uses operating profit of each reportable segment presented in accordance with K-IFRS (“segment operating profit”) in its assessment of the profitability of each reportable segment. The sum of segment operating profit for all four reportable segments differs from our operating profit presented in accordance with IFRS as issued by the IASB as segment operating profit does not include certain items such as donations, gain and loss from disposal of property and equipment and intangible assets and impairment loss on property and equipment and intangible assets. For a reconciliation of operating profit presented in accordance with IFRS as issued by the IASB and operating profit presented in accordance with K-IFRS, see “— Explanatory Note Regarding Presentation of Certain Financial Information under K-IFRS.” In addition to the information set forth below, see note 5 of the notes to our consolidated financial statements for more detailed information regarding each of our reportable segments.

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A number of recent developments have had or are expected to have a material impact on our results of operations, financial condition and capital expenditures. These developments include:

New Rate Regulations.    Under the MDDIA, wireless telecommunications service providers are obliged to provide certain benefits, such as discounted rates, to subscribers who subscribe to their service without receiving handset subsidies. Handset subsidies are provided to subscribers who agree to use our service for a predetermined service period and purchase handsets on an installment basis. In June 2017, the State Affairs Planning Advisory Committee of Korea announced that it would encourage wireless telecommunications service providers, including us, to increase the applicable discount rate offered to subscribers from 20% to 25%, which we adopted in September 2017, and to offer additional discounts to low income customers, including those on government welfare programs and senior citizen recipients of the basic pension, which we implemented in December 2017 and July 2018, respectively.

In 2018, the number of subscribers who elected to receive discounted rates in lieu of receiving handset subsidies pursuant to the MDDIA increased due to greater public awareness of the availability of such discounted rates as well as the increase in the applicable discount rate to 25%. In the fourth quarter of 2018, approximately 44% of our new subscribers elected to receive discounted rates in lieu of handset subsidies compared to 40% in the previous quarter. As of December 31, 2018, approximately 85% of our subscribers who elected to receive these discounted rates are receiving the increased 25% rate discount. These Government measures have adversely affected our revenues and results of operations as more subscribers elected to receive the 25% rate discount. On the other hand, this has also led to a reduction of our marketing expenses as the number of subscribers who have elected to receive handset subsidies has declined, and has contributed to maintaining a stable churn rate.

With respect to handset subsidies, in October 2014, the Government started limiting the amount of subsidies a wireless telecommunications service provider can provide to subscribers in order to prevent excessive competition among wireless telecommunications service providers under the MDDIA. The prohibition from providing handset subsidies exceeding the amount set by the KCC (which was Won 330,000 from April 2015 to September 2017) expired in September 2017 pursuant to the expiration of the three-year effective period of the relevant provision of the MDDIA. Although the expiration of this provision may lead to increased handset subsidies provided to subscribers among us and our competitors, we do not believe the impact to have been significant to date, as a greater number of subscribers have elected to receive discounted rates in lieu of such subsidies due to the increase in the applicable discount rate to 25% in September 2017. Failure to comply with the MDDIA may lead to suspension of our business or imposition of monetary penalties. For more information about the MDDIA and the penalties imposed for violating Government regulations, see “Item 4.B. Business Overview — Law and Regulation — Rate Regulation” and “Item 8.A. Consolidated Statements and Other Financial Information — Legal Proceedings — KCC Proceedings.”

Decrease in Interconnection Fees.    Our wireless telecommunications services depend, in part, on our interconnection arrangements with domestic and international fixed-line and other wireless networks. Charges for interconnection affect our revenues and operating results. The MSIT determines the basic framework for interconnection arrangements, including policies relating to interconnection rates in Korea. Under our interconnection agreements, we are required to make payments in respect of calls which originate from our networks and terminate in the networks of other Korean telecommunications operators, and the other operators are required to make payments to us in respect of calls which originate in their networks and terminate in our network. The MSIT has continued to gradually decrease the interconnection rates in Korea, which has led to a continued decrease in our interconnection revenue as well as interconnection expenses from 2012 to 2018 and any further reduction in interconnection rates by the MSIT may continue to impact our results of operations. Beginning in 2017, a single interconnection rate paid by fixed-line network service providers for fixed-line to wireless calls applies to all wireless telecommunications service providers. For more information about our interconnection revenue and expenses, see “Item 4.B. Business Overview — Interconnection.”

Decrease in Monthly Revenue per Subscriber.    We measure monthly average revenue per subscriber using two metrics: average monthly revenue per subscriber excluding MVNO subscribers leasing our networks (“ARPU”) and average monthly revenue per subscriber including such MVNO subscribers (“ARPU including MVNO”). ARPU is derived by dividing the sum of total SK Telecom revenues on a separate basis from voice service and data

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service for the period (excluding revenue derived from MVNO subscribers leasing our networks) by the monthly average number of subscribers (excluding the number of MVNO subscribers) for the period, then dividing that number by the number of months in the period. ARPU including MVNO is derived by dividing the sum of total SK Telecom revenues on a separate basis from voice service and data service for the period (including revenue derived from MVNO subscribers) by the monthly average number of subscribers (including the number of MVNO subscribers) for the period, then dividing that number by the number of months in the period.

Our ARPU decreased by 7.6% to Won 32,243 in 2018 from Won 34,901 in 2017, which represented a decrease of 1.3% from Won 35,360 in 2016. Our ARPU including MVNO decreased by 8.2% to Won 28,615 in 2018 from Won 31,171 in 2017, which represented a decrease of 2.4% from Won 31,933 in 2016. The decreases in ARPU and ARPU including MVNO in 2018 and 2017 were primarily due to a decrease in revenue attributable to an increase in the number of subscribers who elected to receive discounted rates in lieu of receiving handset subsidies, as well as the increase in such discount rate from 20% to 25% starting in September 2017, offset in part by an increase in subscribers that subscribe to our higher-priced unlimited data usage plans. In addition, the decreases in ARPU and ARPU including MVNO in 2018 were also partially due to the additional rate discounts offered to low income customers, including those on government welfare programs and senior citizen recipients of the basic pension, starting in December 2017 and July 2018, respectively.

Explanatory Note Regarding Presentation of Certain Financial Information under K-IFRS

In addition to preparing consolidated financial statements in accordance with IFRS as issued by the IASB included in this annual report, we also prepare financial statements in accordance with K-IFRS as adopted by the KASB, which we are required to file with the FSC and the Korea Exchange under the FSCMA.

K-IFRS requires operating profit, which is calculated as operating revenue less operating expense, to be separately presented on the consolidated statement of income. The presentation of operating profit in our consolidated statements of income prepared in accordance with IFRS as issued by the IASB included in this annual report differs from the presentation of operating profit in the consolidated statements of income prepared in accordance with K-IFRS for the corresponding periods in certain respects. The table below sets forth a reconciliation of our operating profit as presented in our consolidated statements of income prepared in accordance with IFRS as issued by the IASB for each of the three years ended December 31, 2018 to the operating profit as presented in the consolidated statements of income prepared in accordance with K-IFRS.

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However, there is no impact on profit for the year or earnings per share for each of the three years ended December 31, 2018, 2017 and 2016.

Critical Accounting Policies, Estimates And Judgments

Our consolidated financial statements are prepared in accordance with IFRS as issued by the IASB. The preparation of the consolidated financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses as well as the disclosure of contingent assets and liabilities. We continually evaluate our estimates and judgments including those related to allowances for doubtful accounts, fair value measurements of financial instruments, estimated useful lives and impairment of long-lived assets, impairment of goodwill, provisions, retirement benefit plans and income taxes. We base our estimates and judgments on historical experience and other factors that are believed to be reasonable under the circumstances. Actual results may differ from these estimates under different assumptions or conditions. We believe that of our significant accounting policies, the following may involve a higher degree of judgment or complexity:

Loss Allowances

A loss allowance is provided based on a review of the status of individual receivable accounts at the end of the year. We maintain loss allowances for estimated losses that result from the inability of our customers to make required payments. We base our allowances on the likelihood of recoverability of accounts receivable based on the aging of accounts receivable at the end of the period, past customer default experience and their credit status, and economic and industrial factors. In addition, following our adoption of IFRS 9, Financial Instruments, in the fiscal year beginning January 1, 2018, we use an “expected credit loss” impairment model to estimate our loss allowances based on the above-described criteria. Under such model, loss allowances are recorded prior to experiencing delinquency on our receivable accounts rather than upon actual delinquency, which was the case under the previously applicable accounting standards. See “— Recently Adopted International Financial Reporting Standards — IFRS 15 and IFRS 9.” Loss allowance amounted to Won 376.0 billion as of December 31, 2018 and Won 362.2 billion as of December 31, 2017. If economic or specific industry trends worsen beyond our estimates, the loss allowances we have recorded may be materially adjusted in the future.

Fair Value Measurement of Financial Instruments

Subsequent to initial recognition, financial assets at fair value through profit or loss, financial assets at fair value through other comprehensive income and derivative financial assets are stated at fair value with any gains or losses arising on remeasurement recognized in profit for the period or other comprehensive income. When measuring fair value, we use quoted prices in active markets to the extent such prices exist. The fair values of financial instruments, including derivative instruments, that are not traded in an active market are determined using valuation techniques that require management’s estimates of future cash flows and discount rates. Our management uses its judgment to select a variety of methods and makes assumptions that are mainly based on market conditions existing at the end of each reporting period. See notes 2(4) and 36(3) of the notes to our consolidated financial statements.

Impairment of Long-lived Assets Including Frequency Usage Rights

Long-lived assets generally consist of property and equipment and intangible assets. We review our depreciation and amortization methods, estimated useful lives and residual values of long-lived assets at the end of each annual reporting period. An impairment loss is recognized when the asset’s recoverable amount is less than its carrying amount. The recoverable amount of a long-lived asset is the greater of an asset’s fair value less costs to sell and its value in use. For the purpose of assessing impairment, we review the recoverable amount of an individual asset or, if it is not possible to measure the individual recoverable amount of an asset, at the level of a cash-generating unit. The recoverable amounts of assets or cash-generating units are determined based on value-in-use calculations, which require the use of estimates. If any such asset or cash-generating unit is considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the asset or cash-generating unit exceeds the estimated recoverable amount.

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Our intangible assets include our frequency usage rights, which have contractual lives of 5 to 10.25 years and are amortized from the date commercial service is initiated through the end of their contractual lives. Because the use of frequency usage rights is exposed to risks and challenges associated with our business, any or all of which, if realized or not properly addressed, may have a material adverse effect on our financial condition, results of operations and cash flows, we review the frequency usage rights for impairment on an annual basis. In connection with our review, we utilize the estimated long-term revenue and cash flow forecasts. The use of different assumptions within our cash flow model could result in different recoverable amounts for our frequency usage rights. The results of our review using the testing method described above resulted in no impairment of our frequency usage rights in 2018. See note 16 of the notes to our consolidated financial statements.

Impairment of Goodwill

Goodwill is measured as the excess of the sum of: (1) the consideration transferred, (2) the amount of any non-controlling interests in the acquiree and (3) the fair value of the acquirer’s previously held equity interest in the acquiree (if any), over the net fair value of the acquisition-date amounts of the identifiable assets acquired and the liabilities assumed. Goodwill is not depreciated, but tested for impairment at the end of each annual reporting period or whenever there is an indication that the asset may be impaired. Goodwill is carried at cost less accumulated impairment losses and the impairment losses are not reversed. For the purpose of impairment testing, we review the recoverable amount of an individual asset or, if it is not possible to measure the individual recoverable amount of an asset, at the level of a cash-generating unit. The recoverable amount of an asset or cash-generating unit to which goodwill has been allocated is the greater of its value in use and its fair value less costs to sell. The value in use calculation requires our management to estimate the future cash flows expected related to the respective cash-generating unit and the determination of an appropriate discount rate in order to calculate present value.

In 2018, we recognized Won 166.8 billion of impairment losses on goodwill compared to Won 33.4 billion of such losses in 2017, which increase was mainly due to our recognition of impairment losses on goodwill relating to our consolidated subsidiary Shopkick, Inc. (“Shopkick”), which operates “shopkick,” a mobile reward points-based in-store shopping application. The recoverable amount of goodwill as of December 31, 2018 relating to Shopkick, which we have classified as a single cash-generating unit, was determined based on fair value less cost of disposal, and such fair value was estimated based on the bidding prices submitted by multiple third parties in their respective letters of intent in connection with our strategic review relating to Shopkick. See note 15 of the notes to our consolidated financial statements.

Income Taxes

We are required to estimate the amount of tax payable or refundable for the current year and the deferred income tax liabilities and assets for the future tax consequences of events that have been reflected in our financial statements or tax returns. This process requires management to make assessments regarding the timing and probability of the tax impact. Actual income taxes could vary from these estimates due to future changes in income tax law or unpredicted results from the final determination of each year’s liability by taxing authorities. We believe that the accounting estimate related to assessment of deferred tax assets for recoverability is a “critical accounting estimate” because (1) it requires management to make assessments about the timing of future events, including the probability of expected future taxable income and available tax planning opportunities and (2) the impact that changes in actual performance versus these estimates could have on the realization of tax benefits as reported in our results of operations could be material. Management’s assumptions require significant judgment because actual performance has fluctuated in the past and may continue to do so. As of December 31, 2018 and 2017, unused tax loss carryforwards of Won 849.9 billion and Won 921.3 billion, respectively, were not recognized as deferred tax assets because we did not believe that their realization would be probable. The decrease of Won 71.4 billion in unrecognized tax loss carryforwards in 2018 compared to 2017 was primarily related to the recognition of certain unused tax loss carryforwards that were previously not recognized as deferred tax assets relating to SK Broadband based on our determination that the probability of their realization has increased. See note 32 of the notes to our consolidated financial statements.

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Prepaid Expenses

We pay commissions to our retail stores and authorized dealers in connection with acquiring wireless and fixed-line telecommunications subscriber contracts, which would not have been paid if there were no binding contracts with subscribers. Following our adoption of IFRS 15, Revenue from Contracts with Customers, in the fiscal year beginning January 1, 2018, we capitalize certain costs associated with such commissions as prepaid expenses and amortize them over the expected periods over which we expect to maintain such subscribers under contract. Our management assesses such expected contract periods based on our historical subscriber churn rate. If we experience any changes in our historical subscriber churn rates, or if our management decides to use other factors for the determination of the expected contract periods, our estimate of the expected contract period will change, which in turn will affect the rate at which the applicable prepaid expenses are amortized and recognized as our operating expenses. See note 8 of the notes to our consolidated financial statements.

Recently Adopted International Financial Reporting Standards — IFRS 15 and IFRS 9

We adopted IFRS 15, Revenue from Contracts with Customers, and IFRS 9, Financial Instruments, in the fiscal year beginning on January 1, 2018.

IFRS 15 is a new accounting standard issued by the IASB that provides a comprehensive framework for determining whether, how much and when revenue is recognized. Pursuant to IFRS 15, we allocate revenue generated from our wireless and fixed-line telecommunication services based on our identification and satisfaction of our stand-alone performance obligations under applicable customer contracts. For example, in the case of contracts where we sell both a wireless device and subscription plan together to a single customer, from which a substantial portion of our overall revenue is generated, we allocate the portion of the overall transaction price related to the wireless device and immediately recognize such portion as revenue, whereas the portion related to the wireless subscription plan is allocated and recognized as revenue over the course of the customer contract period. Under IFRS 15, such allocation is made proportionately based on the stand-alone selling prices of the wireless device and subscription plan.

In addition to the revenue recognition model, IFRS 15 specifies how to account for the incremental costs of obtaining a contract, which in our case includes certain of our commissions paid to our retail stores and authorized dealers in connection with acquiring new customer contracts. IFRS 15 requires certain of such costs to be capitalized as assets and subsequently amortized over the applicable expected contract periods calculated based on our historical subscriber churn rate. See note 3(1) of the notes to our annual consolidated financial statements for further details regarding the effects of our adoption of IFRS 15.

IFRS 9 requires all financial assets, on initial recognition, to be classified as financial assets at amortized cost, debt instruments at fair value through other comprehensive income, equity investments at fair value through other comprehensive income or financial assets at fair value through profit or loss. The classification is generally based on the business model in which a financial asset is managed and its contractual cash flow characteristics. In addition, IFRS 9 sets out an “expected credit loss” impairment model, under which we generally recognize impairment losses on debt instruments at an amount equal to their twelve-month expected credit losses. However, with respect to debt instruments experiencing a significant increase in credit risk and accounts receivable – trade, we recognize impairment losses at an amount equal to their lifetime expected credit losses. See note 3(2) to the notes to our annual consolidated financial statements for further details regarding the effects of our adoption of IFRS 9.

We adopted IFRS 15 and IFRS 9 by recognizing the cumulative effect of initially applying IFRS 15 and IFRS 9 as adjustments to the opening balance of retained earnings as of January 1, 2018. We elected to apply IFRS 15 retrospectively only to contracts that were not completed as of January 1, 2018. For a discussion of the adjustments made to line items presented in our consolidated statement of financial position due to the adoption of IFRS 15 and IFRS 9, see note 3(3) of the notes to our annual consolidated financial statements.

In the case of our consolidated statement of income for the year ended December 31, 2018, the adoption of IFRS 15 had the effect of decreasing our operating revenue by Won 85.8 billion, and decreasing advertising expenses and commission expenses by Won 51.2 billion and Won 12.7 billion, respectively, for a total decrease in our operating expense by Won 66.1 billion. Therefore, the adoption of IFRS 15 resulted in decreases in operating

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profit and profit before income tax by Won 19.7 billion each. In addition, the adoption had the effect of decreasing our profit for the year by Won 88.2 billion and increasing our income tax expense by Won 68.5 billion. The adoption of IFRS 9 did not have a material impact on our consolidated statement of income for the year ended December 31, 2018.

The adoption of IFRS 15 and IFRS 9 did not have a material impact on our consolidated statement of cash flows for the year ended December 31, 2018.

International Financial Reporting Standards Issued but Not yet Adopted — IFRS 16

We plan to adopt IFRS 16, Leases, in the fiscal year beginning on January 1, 2019 using the modified retrospective approach by recognizing the cumulative effect of initially applying IFRS 16 as an adjustment to the opening balance of retained earnings as of such date. We have identified and implemented a new system solution to meet the requirements of IFRS 16 and have identified and implemented processes and internal controls to meet the reporting and disclosure requirements under the new standard.

We are currently assessing the impact of the adoption of IFRS 16 on our consolidated results of operations and financial position. Based on our preliminary assessment, we as a lessee expect to recognize right-of-use assets and liabilities related to substantially all of our operating lease arrangements on January 1, 2019. Our current operating lease portfolio subject to such recognition is primarily comprised of cell sites and other real estate, and we currently estimate that the amounts of right-of-use assets and liabilities to be so recognized will range between Won 500 billion and Won 700 billion. Any difference between the amounts of such assets and liabilities will result in an adjustment to the opening balance of retained earnings on January 1, 2019. We also expect lease expenses to decrease and depreciation expenses of the right-of-use assets and interest expenses of lease liabilities to increase. As a lessor, however, we do not expect the adoption of IFRS 16 to have a significant impact on our consolidated results of operations or financial position. See note 4(28) of the notes to our consolidated financial statements for a summary of significant accounting standards that have been issued but not yet adopted.

Operating Results

The following table sets forth summary consolidated income statement information, including that expressed as a percentage of operating revenue and other income, for the periods indicated:

The following table sets forth additional information about our operations with respect to our reportable segments during the periods indicated:

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