UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2(a)

UNDER THE SECURITIES EXCHANGE OF 1934

(Amendment No. 1)*

KEY ENERGY SERVICES, INC.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

49309J103

(CUSIP Number)

S. Kris Agarwal

Platinum Equity, LLC

360 North Crescent Drive

Beverly Hills, CA 90210

(310) 712-1850

With a copy to:

Alison S. Ressler

Sullivan & Cromwell LLP

1888 Century Park East

Los Angeles, CA 90067

(310) 712-6600

(Name, Address and Telephone Number of Person Authorized to

Receive Notices and Communications)

February 25, 2019

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box. ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Exchange Act”) or otherwise subject to the liabilities of that section of the Exchange Act but shall be subject to all other provisions of the Exchange Act (however, see the Notes).

Introductory Note

This Amendment No. 1 to Schedule 13D amends and supplements the Schedule 13D filed with the Securities and Exchange Commission (the “SEC”) on December 27, 2016 (the “Original Schedule 13D”) by the reporting persons identified therein with respect to the common stock, par value $0.01 per share (the “Common Stock”), of Key Energy Services, Inc., a Delaware corporation (the “Company” or “Key”). Unless otherwise stated herein, the Original Schedule 13D remains in full force and effect. Capitalized terms used but not defined have the meaning given them in the Original Schedule 13D.

Item 3 of the Original Schedule 13D is hereby amended by adding the following paragraphs:

On February 25, 2019, Soter purchased 228,335 shares of Common Stock for an aggregate purchase price of $473,384.12 in open market transactions on the New York Stock Exchange.

On February 26, 2019, Soter purchased 25,184 shares of Common Stock for an aggregate purchase price of $57,417.00 in open market transactions on the New York Stock Exchange.

Item 4 of the Original Schedule 13D is hereby amended by amending and restating the final paragraph:

The purpose of the Reporting Persons’ acquisition of the Common Stock and Series A Preferred Stock is long-term investment. As stated above, subject to certain exceptions, the directors appointed by the Reporting Persons will control decisions made by the Board through at least the Initial Board Term, and past such period for as long as the Series A Preferred Stock remains outstanding. Consequently, through such board control, the Reporting Persons have the ability generally to direct the operations and business strategy of the Company, which may include, subject to certain approval rights set forth in the Charter and By-laws, plans relating to acquisitions or dispositions of its securities, an extraordinary corporate transaction involving the Company (such as a merger, reorganization or liquidation), sale of its assets, management changes, change in capitalization or dividend policy, changes in business or corporate structure and other matters described in clauses (a) through (j) of Item 4 of Schedule 13D. In addition, the Reporting Persons have acquired $30,000,000 of aggregate principal amount of the Company’s term loans under the Term Loan Facility among the Company, as borrower, certain subsidiaries of the Company, as guarantors, and the lenders named therein. The Reporting Persons may, from time to time, acquire additional shares of Common Stock and/or other equity, debt, notes, instruments or securities, or rights convertible into or exchangeable or exercisable for Common Stock or such other equity, debt, notes, instruments or securities of, the Company (collectively, “Securities”) or dispose of Securities on the open market or otherwise. The Reporting Persons may also participate in any equity or debt financing transactions the Company decides to pursue. Except as described above, the Reporting Persons have no present plans or proposals which would result in the matters described in clauses (a) through (j) of Item 4 of Schedule 13D.

Item 5 of the Schedule 13D is hereby amended and restated in its entirety:

The information set forth or incorporated in Item 3 and Item 4 and Rows 7 through 13 of the cover pages of this Schedule 13D is hereby incorporated by reference.

(a)-(b) The following sets forth the aggregate number of shares and percentage of Common Stock beneficially owned by each of the Reporting Persons, as well as the number of shares of Common Stock as to which each Reporting Person has the sole power to vote or to direct the vote, shared power to vote or to direct the vote, sole power to dispose or to direct the disposition, or shared power to dispose or to direct the disposition based on 20,297,359 shares of Common Stock outstanding as of November 5, 2018 as reported in the Company’s Quarterly Report on Form 10-Q, filed with the SEC on November 7, 2018.

The power to vote or to direct the vote of shares of Common Stock described in the table above is subject to the restrictions described in Item 6, which are incorporated herein by reference.

(c) Except as set forth herein, to the knowledge of any of the Reporting Persons, none of the Reporting Persons has engaged in any transaction during the past 60 days in any shares of Common Stock.

(d) To the knowledge of any of the Reporting Persons, no other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported in this Item 5.

(e) Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Schedule 13D is true, complete and correct.

Dated: February 26, 2019

EXHIBIT INDEX