Exhibit 99.5

ATHLON ENERGY INC.

UNAUDITED PRO FORMA FINANCIAL STATEMENTS

INTRODUCTION

Athlon Energy Inc. (“Athlon”), a Delaware corporation incorporated on April 1, 2013, is an independent exploration and production company focused on the acquisition, development, and exploitation of unconventional oil and liquids-rich natural gas reserves in the Permian Basin.  On June 2, 2014 and June 3, 2014, Athlon acquired certain oil and natural gas properties and related assets in the Midland Basin from Hibernia Holdings, LLC (“Hibernia”) and Piedra Energy II, LLC (“Piedra”), respectively, for approximately $675.1 million in cash, in the aggregate (the “Acquisitions”).  The accompanying unaudited pro forma financial statements give effect to the Acquisitions, including related financing transactions.  The unaudited pro forma balance sheet assumes that the Acquisitions and related financing transactions occurred on March 31, 2014.  The unaudited pro forma statements of operations assume that the Acquisitions and related financing transactions occurred on January 1, 2013.

The accompanying unaudited pro forma financial statements should be read together with:

·                  Athlon’s unaudited consolidated financial statements included in its Quarterly Report on Form 10-Q for the quarter ended March 31, 2014, filed with the SEC on May 12, 2014;

·                  Athlon’s audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2013, filed with the SEC on March 3, 2014;

·                  Hibernia Energy LLC’s unaudited consolidated financial statements as of and for the quarter ended March 31, 2014, included as Exhibit 99.1 to this Current Report on Form 8-K/A;

·                  Hibernia Energy LLC’s audited consolidated financial statements as of and for the year ended December 31, 2013, included as Exhibit 99.3 to this Current Report on Form 8-K/A;

·                  Piedra’s unaudited Schedule of Direct Operating Revenues and Direct Operating Expenses of Certain Oil and Natural Gas Properties for the quarter ended March 31, 2014, included as Exhibit 99.2 to this Current Report on Form 8-K/A; and

·                  Piedra’s audited Schedule of Direct Operating Revenues and Direct Operating Expenses of Certain Oil and Natural Gas Properties for the year ended December 31, 2013, included as Exhibit 99.3 to Athlon’s Current Report on Form 8-K filed with the SEC on April 9, 2014.

The accompanying unaudited pro forma financial statements were derived by making certain adjustments to Athlon’s historical consolidated financial statements.  The adjustments are based on currently available information and certain estimates and assumptions.  Therefore, the actual adjustments may differ from the pro forma adjustments.  However, management believes that the assumptions provide a reasonable basis for presenting the significant effects of the transactions as contemplated and that the pro forma adjustments give appropriate effect to those assumptions and are properly applied in the unaudited pro forma financial statements.

The unaudited pro forma financial statements and related notes are presented for illustrative purposes only.  If the Acquisitions and related financing transactions had occurred in the past, Athlon’s operating results might have been materially different from those presented in the unaudited pro forma financial statements.  The unaudited pro forma financial statements should not be relied upon as an indication of operating results that Athlon would have achieved if the Acquisitions and related financing transactions had taken place on the specified date.  In addition, future results may vary significantly from the results reflected in the unaudited pro forma statements of operations and should not be relied on as an indication of the future results Athlon will have after the completion of the Acquisitions and related financing transactions.

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ATHLON ENERGY INC.

UNAUDITED PRO FORMA BALANCE SHEET

March 31, 2014

(in thousands)

The accompanying notes are an integral part of these unaudited pro forma financial statements.

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ATHLON ENERGY INC.

UNAUDITED PRO FORMA STATEMENT OF OPERATIONS

For the Quarter Ended March 31, 2014

(in thousands, except per share amounts)

The accompanying notes are an integral part of these unaudited pro forma financial statements.

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ATHLON ENERGY INC.

UNAUDITED PRO FORMA STATEMENT OF OPERATIONS

For the Year Ended December 31, 2013

(in thousands, except per share amounts)

The accompanying notes are an integral part of these unaudited pro forma financial statements.

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ATHLON ENERGY INC.

NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS

Note 1.         Basis of Presentation

Athlon’s historical financial information as of and for the three months ended March 31, 2014 is derived from Athlon’s consolidated financial statements included in its Quarterly Report on Form 10-Q for the quarter ended March 31, 2014.  Athlon’s historical financial information for the year ended December 31, 2013 is derived from Athlon’s consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2013.

Hibernia Energy LLC’s historical financial information as of and for the three months ended March 31, 2014 is derived from its unaudited consolidated financial statements, which are included as Exhibit 99.1 to this Current Report on Form 8-K/A.  Hibernia Energy LLC’s historical financial information for the year ended December 31, 2013 is derived from its audited consolidated financial statements, which are included as Exhibit 99.3 to this Current Report on Form 8-K/A.

Piedra’s historical financial information for the three months ended March 31, 2014 is derived from its unaudited Schedule of Direct Operating Revenues and Direct Operating Expenses of Certain Oil and Natural Gas Properties, which is included as Exhibit 99.2 to this Current Report on Form 8-K/A.  Piedra’s historical financial information for the year ended December 31, 2013 is derived from its audited Schedule of Direct Operating Revenues and Direct Operating Expenses of Certain Oil and Natural Gas Properties, which is included as Exhibit 99.3 to Athlon’s Current Report on Form 8-K filed with the SEC on April 9, 2014.  Piedra’s Schedules of Direct Operating Revenues and Direct Operating Expenses of Certain Oil and Natural Gas Properties are not intended to be a complete presentation of the results of operations of the properties, as they do not include general and administrative expenses, effects of derivative transactions, interest income or expense, depreciation, depletion, and amortization, any provision for income tax expenses, and other income and expense items not directly associated with direct operating revenues from natural gas, natural gas liquids, and crude oil.  As such, they are not indicative of the operating results of the Piedra assets going forward.

For purposes of the unaudited pro forma balance sheet, it is assumed that the Acquisitions and related financing transactions occurred on March 31, 2014.  For purposes of the unaudited pro forma statements of operations, it is assumed that the Acquisitions and related financing transactions occurred on January 1, 2013.

Note 2.         Pro Forma Adjustments and Assumptions

Athlon made the following adjustments and assumptions in the preparation of the unaudited pro forma balance sheet:

(a)         Reflects gross proceeds of approximately $592.3 million from the April 2014 issuance and sale of 14,806,250 shares of common stock at an offering price of $40.00 per share, net of underwriting discounts and commissions of approximately $20.7 million, in the aggregate, and additional offering expenses of approximately $0.7 million.

(b)         Reflects gross proceeds of $650 million from the May 2014 issuance of 6% senior notes due 2022 (the “2022 Notes”), net of initial purchasers’ gross spread of approximately $9.8 million, in the aggregate, and additional debt issuance costs of approximately $1.1 million.

(c)          On April 11, 2014, Athlon received firm commitments from the lenders under its credit agreement to increase the borrowing base from $525 million to $1.0 billion.  Reflects estimated debt issuance costs associated with this borrowing base redetermination.  The borrowings base was ultimately increased to $837.5 million as a result of the issuance of the 2022 Notes.

(d)         Reflects the use of a portion of the net proceeds from the April 2014 issuance and sale of 14,806,250 shares of common stock to eliminate outstanding borrowings under Athlon’s credit agreement.

(e)          To eliminate the assets, liabilities, and members’ equity not acquired or assumed from Hibernia in the Acquisitions, to record the Acquisitions for $675.1 million in cash, and to allocate the purchase price to the assets acquired and liabilities assumed.  The allocation of the purchase price to the assets acquired and liabilities assumed is preliminary and, therefore, subject to change.

The allocation of the purchase price of the Acquisitions to the fair value of the assets acquired and liabilities assumed is as follows (in thousands):

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ATHLON ENERGY INC.

NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS — Continued

(f)           Reflects estimated incremental acquisition costs incurred in connection with the consummation of the Acquisitions.  As of March 31, 2014, Athlon had incurred $0.4 million of acquisitions costs and expects total acquisitions costs to be approximately $0.8 million.

Athlon made the following adjustments and assumptions in the preparation of the unaudited pro forma statements of operations:

(a)         Reflects the April 2014 issuance and sale of 14,806,250 shares of common stock.

(b)         Reflects estimated incremental interest expense and amortization of debt issuance costs associated with the issuance of the 2022 Notes.

(c)          A portion of the assets acquired by Hibernia were acquired by them during May 2013.  Reflects the incremental oil and natural gas revenues and production costs associated with those assets from January 1, 2013 through the date Hibernia acquired them.

(d)         Reflects incremental depletion, depreciation, and amortization of oil and natural gas properties associated with the Acquisitions.  Costs associated with evaluated properties are amortized using a unit-of-production basis under the full cost method of accounting for oil and natural gas properties.

(e)          Reflects estimated acquisition costs incurred in connection with the consummation of the Acquisitions.  As of March 31, 2014, Athlon had incurred $0.4 million of acquisitions costs and expects total acquisitions costs to be approximately $0.8 million.

(f)           Reflects incremental accretion of discount on asset retirement obligations associated with the Acquisitions.

(g)          Reflects an increase in unused commitment fees and amortization of debt issuance costs related to Athlon’s credit agreement, partially offset by the elimination of interest expense associated with outstanding borrowings under Athlon’s credit agreement.  On a pro forma basis, there would have been no outstanding borrowings under Athlon’s credit agreement as of January 1, 2013.

A 1/8% change in LIBOR would have no effect on Athlon’s interest expense as there would have been no variable rate debt outstanding during the periods presented on a pro forma basis.

(h)         Reflects estimated decrease in income tax provision associated with the reduction in operating income from the Acquisitions and the pro forma adjustments using Athlon’s effective tax rate of 35.1% and 24.1% for the three months ended March 31, 2014 and the year ended December 31, 2013, respectively.  This rate is inclusive of federal, state, and local income taxes and differs from the statutory rate as Athlon has only been subject to federal income tax as a subchapter C corporation since the date of its incorporation.

(i)             Athlon is the sole managing partner of Athlon Holdings LP and owns less than 100% of the economic interest in Athlon Holdings LP, but has 100% of the voting power and controls the management of Athlon Holdings LP.  Upon consummation of the April 2014 issuance and sale of 14,806,250 shares of common stock, Athlon’s ownership percentage of Athlon Holdings LP increased, resulting in a decrease in the noncontrolling interest from approximately 2.2% to approximately 1.9%.  Reflects estimated decrease in net income attributable to noncontrolling interest based on pro forma income before income taxes.

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ATHLON ENERGY INC.

NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS — Continued

Note 3. Pro Forma Earnings Per Share

The following table reflects the pro forma allocation of net income to Athlon’s common stockholders and earnings per share (“EPS”) computations for the periods indicated:

(a)         For the three months ended March 31, 2014 and for the year ended December 31, 2013, 1,855,563 New Holdings Units were outstanding but excluded from the pro forma EPS calculations because their effect would have been antidilutive.

Note 4.         Supplementary Information

There are numerous uncertainties inherent in estimating quantities of proved reserves and in projecting future rates of production and timing of development expenditures.  Oil and natural gas reserve engineering is and must be recognized as a subjective process of estimating underground accumulations of oil and natural gas that cannot be measured in any exact way, and estimates of other engineers might differ materially from those included herein.  The accuracy of any reserve estimate is a function of the quality of available data and engineering, and estimates may justify revisions based on the results of drilling, testing, and production activities.  Accordingly, reserve estimates are often materially different from the quantities of oil and natural gas that are ultimately recovered.  Reserve estimates are integral to management’s analysis of impairment of oil and natural gas properties and the calculation of depletion, depreciation, and amortization on these properties.  Natural gas volumes include natural gas liquids.

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ATHLON ENERGY INC.

NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS — Continued

Athlon’s estimated pro forma net quantities of proved reserves were as follows as of December 31, 2013:

The changes in Athlon’s pro forma proved reserves were as follows for 2013: