FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * CHESAPEAKE ENERGY CORP   2. Issuer Name and Ticker or Trading Symbol Bronco Drilling Company, Inc. [BRNC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 6100 NORTH WESTERN AVENUE 3. Date of Earliest Transaction (Month/Day/Year) 06/06/2011 (Street) OKLAHOMA CITY, OK 73118 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, par value $0.01 per share (1) (2) 06/06/2011   P   24,278,257 A $ 11 24,278,257 I See Footnote (3) Common Stock, par value $0.01 per share (4) 06/06/2011   P   63,550,899 A $ 11 87,829,156 I See Footnote (3) Common Stock, par value $0.01 per share 06/06/2011   P   4,521,802 (5) A $ 11 1,000 (6) I See Footnote (3)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
CHESAPEAKE ENERGY CORP 6100 NORTH WESTERN AVENUE OKLAHOMA CITY, OK 73118		X
CHESAPEAKE OPERATING INC 6100 NORTH WESTERN AVENUE OKLAHOMA CITY, OK 73118		X
CHESAPEAKE OILFIELD SERVICES LLC 6100 NORTH WESTERN AVENUE OKLAHOMA CITY, OK 73118		X
NOMAC DRILLING LLC 6100 NORTH WESTERN AVENUE OKLAHOMA CITY, OK 73118		X
Nomac Acquisition, Inc. 6100 NORTH WESTERN AVENUE OKLAHOMA CITY, OK 73118		X

Signatures

/s/ Domenic J. Dell'Osso, Jr., Executive Vice President and Chief Financial Officer for CHESAPEAKE ENERGY CORPORATION		06/07/2011
**Signature of Reporting Person		Date
/s/ Domenic J. Dell'Osso, Jr., Executive Vice President and Chief Financial Officer for CHESAPEAKE OPERATING, INC.		06/07/2011
**Signature of Reporting Person		Date
/s/ Domenic J. Dell'Osso, Jr., Executive Vice President and Chief Financial Officer for CHESAPEAKE OILFIELD SERVICES, L.L.C.		06/07/2011
**Signature of Reporting Person		Date
/s/ Domenic J. Dell'Osso, Jr., Executive Vice President and Chief Financial Officer for NOMAC DRILLING, L.L.C.		06/07/2011
**Signature of Reporting Person		Date
/s/ Domenic J. Dell'Osso, Jr., Executive Vice President and Chief Financial Officer for NOMAC ACQUISITION, INC.		06/07/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	This form is a joint filing by Chesapeake Energy Corporation ("Chesapeake"), Chesapeake Operating, Inc., a direct wholly owned subsidiary of Chesapeake ("Operating"), Chesapeake Oilfield Services, L.L.C. ("Oilfield"), a direct wholly owned subsidiary of Operating, Nomac Drilling, L.L.C., a direct wholly owned subsidiary of Oilfield ("Drilling") and Nomac Acquisition Inc., a direct wholly owned subsidiary of Drilling ("Nomac").
(2)	Shares of Common Stock, par value $0.01 per share (the "Shares"), of Bronco Drilling Company, Inc. ("Bronco") acquired pursuant to the tender offer effected pursuant to the Agreement and Plan of Merger, dated as of April 14, 2011 and amended as of May 17, 2011 (as so amended, the "Merger Agreement"), by and among Chesapeake, Nomac and Bronco (such tender offer, the "Offer").
(3)	Shares were held by Nomac. As Nomac is an indirect wholly owned subsidiary of Chesapeake, Operating and Oilfield and a direct wholly owned subsidiary of Drilling, each of Chesapeake, Operating, Oilfield and Drilling may be deemed to have acquired indirect beneficial ownership of the Shares.
(4)	Shares acquired pursuant to the exercise of "top-up" option to purchase additional shares from Bronco, at $11.00 per share, under the terms of the Merger Agreement.
(5)	Reflects all of the outstanding shares of Bronco Drilling Company, Inc. not tendered in the Offer, which may be deemed to have been acquired by Chesapeake and Nomac pursuant to the consummation of the Merger (as defined below).
(6)	Following the exercise of the "top-up" option, Nomac was merged with and into Bronco, with Bronco surviving the Merger as an indirect wholly owned subsidiary of Chesapeake pursuant to a "short-form merger" under Delaware law (the "Merger"). At the effective time of the Merger, all of Bronco's previously outstanding stock held by the registrants were canceled. Prior to the Merger, Drilling directly held, and therefore Chesapeake, Operating and Oilfield may be deemed to have indirectly held, 1,000 shares of Nomac, which represented all of the issued and outstanding capital stock of Nomac. At the effective time of the Merger, each share of Nomac was converted into a share of the surviving company's stock.
Remarks: Exhibit List: Exhibit 99.1 - Joint Filer Information; Exhibit 99.2 - Joint Filer Signatures

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