UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

(Rule 13d-102)

Information Statement Pursuant to Rules 13d-1 and 13d-2

Under the Securities Exchange Act of 1934

(Amendment No. 1 )*

	Athlon Energy Inc.
	(Name of Issuer)

	Common stock, par value $0.01 per share
	(Title of Class of Securities)

	047477104
	(CUSIP Number)

	December 31, 2014
	Date of Event Which Requires Filing of the Statement

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

*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 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Cusip No. 047477104

13G/A

Page 2 of 9 Pages

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Citadel Advisors LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a) ¨

(b) ¨

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

SHARED VOTING POWER

0 shares

SOLE DISPOSITIVE POWER

SHARED DISPOSITIVE POWER

See Row 6 above

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

12.

TYPE OF REPORTING PERSON

IA; OO; HC

Cusip No. 047477104

13G/A

Page 3 of 9 Pages

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Citadel Advisors Holdings II LP

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a) ¨

(b) ¨

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

SHARED VOTING POWER

0 shares

SOLE DISPOSITIVE POWER

SHARED DISPOSITIVE POWER

See Row 6 above

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

12.

TYPE OF REPORTING PERSON

PN; HC

Cusip No. 047477104

13G/A

Page 4 of 9 Pages

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Citadel GP LLC

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a) ¨

(b) ¨

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

SHARED VOTING POWER

0 shares

SOLE DISPOSITIVE POWER

SHARED DISPOSITIVE POWER

See Row 6 above.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above.

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

12.

TYPE OF REPORTING PERSON

OO; HC

Cusip No. 047477104

13G/A

Page 5 of 9 Pages

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Kenneth Griffin

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a) ¨

(b) ¨

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

U.S. Citizen

NUMBER OF

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

SOLE VOTING POWER

SHARED VOTING POWER

0 shares

SOLE DISPOSITIVE POWER

SHARED DISPOSITIVE POWER

See Row 6 above

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

12.

TYPE OF REPORTING PERSON

IN; HC

Cusip No. 047477104

13G/A

Page 6 of 9 Pages

Item 1(a)	Name of Issuer
	Athlon Energy Inc.

Item 1(b)	Address of Issuer’s Principal Executive Offices
	420 Throckmorton Street, Suite 1200, Fort Worth, Texas 76102

Item 2(a)	Name of Person Filing
	This Schedule 13G/A is being jointly filed by Citadel Advisors LLC (“Citadel Advisors”), Citadel Advisors Holdings II LP (“CAH2”), Citadel GP LLC (“CGP”) and Mr. Kenneth Griffin (collectively with Citadel Advisors, CAH2 and CGP, the “Reporting Persons”).

	The filing of this statement shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any securities covered by the statement other than the securities actually owned by such person (if any).

Item 2(b)	Address of Principal Business Office
	The address of the principal business office of each of the Reporting Persons is c/o Citadel LLC, 131 S. Dearborn Street, 32nd Floor, Chicago, Illinois 60603.

Item 2(c)	Citizenship
	Each of Citadel Advisors and CGP is organized as a limited liability company under the laws of the State of Delaware. CAH2 is organized as a limited partnership under the laws of the State of Delaware. Mr. Griffin is a U.S. citizen.

Item 2(d)	Title of Class of Securities
	Common stock, $0.01 par value

Item 2(e)	CUSIP Number
	047477104

Item 3	If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a:

(a)

¨ Broker or dealer registered under Section 15 of the Exchange Act;

(b)

¨ Bank as defined in Section 3(a)(6) of the Exchange Act;

(c)

¨ Insurance company as defined in Section 3(a)(19) of the Exchange Act;

(d)

¨ Investment company registered under Section 8 of the Investment Company Act;

(e)

¨ An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);

(f)

¨ An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);

Cusip No. 047477104

13G/A

Page 7 of 9 Pages

(g)

¨ A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);

(h)

¨ A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;

(i)

¨ A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act;

(j)

¨ Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

If filing as a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please specify the type of institution: ____________.

Item 4

Ownership

Citadel Advisors LLC

(a)

Citadel Advisors may be deemed to beneficially own 0 shares of Common Stock.

(b)

The number of shares Citadel Advisors may be deemed to beneficially own constitutes 0% of the Common Stock outstanding.

(c)

Number of shares as to which such person has:

(i)

sole power to vote or to direct the vote: 0

(ii)

shared power to vote or to direct the vote: 0

(iii)

sole power to dispose or to direct the disposition of: 0

(iv)

shared power to dispose or to direct the disposition of: 0

Citadel Advisors Holdings II LP

(a)

CAH2 may be deemed to beneficially own 0 shares of Common Stock.

(b)

The number of shares CAH2 may be deemed to beneficially own constitutes 0% of the Common Stock outstanding.

(c)

Number of shares as to which such person has:

(i)

sole power to vote or to direct the vote: 0

(ii)

shared power to vote or to direct the vote: 0

(iii)

sole power to dispose or to direct the disposition of: 0

(iv)

shared power to dispose or to direct the disposition of: 0

Cusip No. 047477104

13G/A

Page 8 of 9 Pages

Citadel GP LLC and Kenneth Griffin

(a)

CGP and Griffin may be deemed to beneficially own 0 shares of Common Stock.

(b)

The number of shares CGP and Griffin may be deemed to beneficially own constitutes 0% of the Common Stock outstanding.

(c)

Number of shares as to which such person has:

(i)

sole power to vote or to direct the vote: 0

(ii)

shared power to vote or to direct the vote: 0

(iii)

sole power to dispose or to direct the disposition of: 0

(iv)

shared power to dispose or to direct the disposition of: 0

Item 5

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following x.

Item 6

Ownership of More than Five Percent on Behalf of Another Person

Not Applicable

Item 7

Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company

See Item 2 above

Item 8

Identification and Classification of Members of the Group

Not Applicable

Item 9

Notice of Dissolution of Group

Not Applicable

Item 10

Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Cusip No. 047477104

13G/A

Page 9 of 9 Pages

After reasonable inquiry and to the best of its knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated this 17th day of February, 2015.

CITADEL ADVISORS LLC		CITADEL ADVISORS HOLDINGS II LP

By:	/s/ Mark Polemeni	By:	/s/ Mark Polemeni
	Mark Polemeni, Authorized Signatory		Mark Polemeni, Authorized Signatory

CITADEL GP LLC		KENNETH GRIFFIN

By:	/s/ Mark Polemeni	By:	/s/ Mark Polemeni
	Mark Polemeni, Authorized Signatory		Mark Polemeni, attorney-in-fact*

Mark Polemeni is signing on behalf of Kenneth Griffin as attorney-in-fact pursuant to a power of attorney previously filed with the Securities and Exchange Commission on January 18, 2013, and hereby incorporated by reference herein. The power of attorney was filed as an attachment to a filing by Citadel Advisors LLC on Schedule 13G for TiVo Inc.

Athlon Energy Inc. SC 13G/A