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SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K/A

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

July 2, 2012

(Date of Report (Date of Earliest Event Reported))

EXTRA SPACE STORAGE INC.

(Exact Name of Registrant as Specified in Its Charter)

2795 East Cottonwood Parkway, Suite 400

Salt Lake City, Utah 84121

(Address of Principal Executive Offices)

(801) 365-4600

(Registrant’s Telephone Number, Including Area Code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o      Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o      Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o      Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o      Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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This Current Report on Form 8-K/A is being filed by Extra Space Storage Inc. (the “Company”) to provide the financial statements that were previously omitted in Item 9.01 of the Current Report on Form 8-K filed on July 9, 2012, relating to the acquisition of the 94.9% equity ownership interest of Prudential Real Estate Investors (“PREI®”) in ESS PRISA III LLC, a joint venture established by the Company and PREI in 2005, resulting in full ownership by the Company.

Item 9.01 Financial Statements and Exhibits.

(a)   Financial Statements of Properties Acquired.

Audited historical financial statements and unaudited interim financial statements for ESS PRISA III LLC:

Report of Independent Auditors

Financial Statements for the Three Years Ended December 31, 2011

Notes to the Audited Financial Statements

Unaudited Interim Financial Statements for the Six Months Ended June 30, 2012

Notes to the Unaudited Interim Financial Statements

(b)  Pro Forma Financial Information.

Pro forma financial statements to reflect the Company’s completed acquisition of ESS PRISA III LLC:

1.               Unaudited Pro Forma Condensed Consolidated Balance Sheet as of June 30, 2012

2.               Unaudited Pro Forma Condensed Consolidated Statement of Operations for the Six Months Ended June 30, 2012

3.               Unaudited Pro Forma Condensed Consolidated Statement of Operations for the Year Ended December 31, 2011

(d)  Exhibits

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Index to Financial Statements

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Extra Space Storage Inc.

Unaudited Pro Forma Condensed Consolidated Financial Information

On July 2, 2012, Extra Space Storage Inc. (the “Company”) completed the acquisition of its joint venture partners’ interest in ESS PRISA III LLC (“PRISA III”) for approximately $300 million.  Prior to this acquisition, PRISA III was a joint venture between the Company and Prudential Real Estate Investors (“PREI®”).  PRISA III’s primary assets consist of 36 self-storage properties located throughout the United States.  Prior to the acquisition, the Company held a 5.1% equity interest in PRISA III, with the remaining equity interests held by PREI.

The acquisition of PREI’s interest in PRISA III was a significant acquisition under Rule 3-14 of Regulation S-X.  Audits were performed on the balance sheets and the related statements of operations of PRISA III for the three-year period ended December 31, 2011.

The following unaudited pro forma condensed consolidated financial information of the Company as of and for the six months ended June 30, 2012 has been derived from (1) the historical unaudited financial statements of the Company as filed in the Company’s Form 10-Q for the six months ended June 30, 2012 and (2) the historical unaudited financial statements of PRISA III for the six months ended June 30, 2012.

The following unaudited pro forma condensed consolidated financial information of the Company as of and for the year ended December 31, 2011 has been derived from (1) the historical audited financial statements of the Company as filed in the Company’s Form 10-K for the year ended December 31, 2011, and (2) the audited historical financial statements of PRISA III for the year ended December 31, 2011.

The unaudited pro forma condensed consolidated balance sheet as of June 30, 2012 reflects adjustments to the Company’s unaudited historical financial data to give effect to the acquisition of PREI’s interest in PRISA III as if it had occurred on June 30, 2012.

The pro forma condensed consolidated statements of operations for the six months ended June 30, 2012 and for the year ended December 31, 2011 reflect adjustments to the Company’s historical financial data to give effect to the acquisition of PREI’s interest in PRISA III as if it had occurred on the first day of each period presented.

The unaudited pro forma adjustments are based on available information. The unaudited pro forma condensed consolidated financial information is not necessarily indicative of what the Company’s actual financial position or results of operations for the period would have been as of the date and for the periods indicated, nor does it purport to represent the Company’s future financial position or results of operations. The unaudited pro forma condensed consolidated financial information should be read, together with the notes thereto, in conjunction with the more detailed information contained in the historical financial statements referenced in this filing.

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Extra Space Storage Inc.

Unaudited Pro Forma Condensed Consolidated Balance Sheet

as of June 30, 2012

(in thousands, except share data)

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Extra Space Storage Inc.

Notes to Unaudited Pro Forma Condensed Consolidated Balance Sheet

as of June 30, 2012

(in thousands, except share data)

(1) Reflects the assets, liabilities and stockholders’ equity of the Company as filed in its Form 10-Q for the six months ended June 30, 2012.

(2) Represents the purchase of PREI’s interest in PRISA III subsequent to June 30, 2012 for $158,382 in cash, and the assumption of a $145,000 note payable.  The purchase price of $322,000 was allocated to the tangible and intangible assets and liabilities acquired based on their fair values.  The values of the tangible assets, consisting of land and buildings were determined as if vacant.  The carrying value of the land and building immediately prior to acquisition was $66,849 and $176,032, respectively. Intangible assets, which represent the value of existing tenant relationships, were recorded at their fair values based on the avoided cost to replace the current leases of, which $5,636 was recorded as part of this acquisition.  The principal value of the note payable approximated its fair value as of the date of purchase. The note was paid in full on July 11, 2012.  The book value at the time of acquisition of all other assets acquired and liabilities approximated fair value.  In addition, the Company revalued its investment in PRISA III immediately prior to the acquisition in accordance with ASC 805-10-25.  This resulted in a non-cash gain of $13,499 at the time of purchase when the investment in the joint venture was written off.

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Extra Space Storage Inc.

Unaudited Pro Forma Condensed Consolidated Statement of Operations

for the Six Months Ended June 30, 2012

(in thousands, except share data)

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Extra Space Storage Inc.

Notes to Unaudited Pro Forma Condensed Consolidated Statement of Operations

for the Six Months Ended June 30, 2012

(in thousands, except share data)

(1) Reflects the results of operations of the Company as filed in its Form 10-Q for the six months ended June 30, 2012.

(2) Represents the pro forma revenues and operating expenses of PRISA III for the period from January 1, 2012 to June 30, 2012, which were not reflected in the historical condensed consolidated statement of operations of the Company.

(3) Adjustment to eliminate the management fee revenue earned by the Company for managing the properties owned by PRISA III.  Prior to the acquisition, the Company managed the properties owned by PRISA III in exchange for a management fee of approximately 6% of cash collected by the properties.  Subsequent to the acquisition by the Company, all properties are self-managed.

(4) Adjustments include depreciation and amortization expense for the period from January 1, 2012 to June 30, 2012, which was not reflected in the historical condensed consolidated statement of operations of the Company.  Adjustments to depreciation and amortization expense are summarized as follows:

(5) Debt of $145,000 was assumed in the acquisition of PREI’s interest in PRISA III.  The debt assumed has a fixed rate of 4.97%.  Adjustments to interest expense represent interest for the period from January 1, 2012 to June 30, 2012, which was not reflected in the historical consolidated condensed statement of operations of the Company.  The amount of interest is calculated as if the acquisition occurred on January 1, 2012.

(6) Interest income was reduced by $221 for the use of net cash in the acquisition as if it had occurred on January 1, 2012.

(7) Adjustment to eliminate the equity in earnings related to PRISA III for the six months ended June 30, 2012.

(8) Income allocated to Preferred Operating Partnership noncontrolling units and Operating Partnership and other noncontrolling units was adjusted to reflect the increase in net income resulting from the acquisition and other pro forma adjustments as follows:

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Extra Space Storage Inc.

Unaudited Pro Forma Condensed Consolidated Statement of Operations

for the Year Ended December 31, 2011

(in thousands, except share data)

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Extra Space Storage Inc.

Notes to Unaudited Pro Forma Condensed Consolidated Statement of Operations

for the Year Ended December 31, 2011

(in thousands, except share data)

(1) Reflects the results of operations of the Company as filed in its Form 10-K for the year ended December 31, 2011.

(2) Represents the pro forma revenues and operating expenses of PRISA III for the year ended December 31, 2011, which were not reflected in the historical condensed consolidated statement of operations of the Company.

(3) Adjustment to eliminate the management fee revenue earned by the Company for managing the properties owned by PRISA III.  Prior to the acquisition, the Company managed the properties owned by PRISA III in exchange for a management fee of approximately 6% of cash collected by the properties.  Subsequent to the acquisition by the Company, all properties are self-managed.

(4) Adjustments include depreciation and amortization expense for the period from January 1, 2011 to December 31, 2011, which was not reflected in the historical condensed consolidated statement of operations of the Company.  Adjustments to depreciation and amortization expense are summarized as follows:

(5) Debt of $145,000 was assumed in the acquisition of PREI’s interest in PRISA III.  The debt assumed has a fixed rate of 4.97%.  Adjustments to interest expense represent interest for the period from January 1, 2011 to December 31, 2011, which was not reflected in the historical consolidated condensed statement of operations of the Company.  The amount of interest is calculated as if the acquisition occurred on January 1, 2011.

(6) Interest income was reduced by $442 for the use of net cash in the acquisition as if the acquisition had occurred on January 1, 2011.

(7) Adjustment to eliminate the equity in earnings related to PRISA III for the year ended December 31, 2011.

(8) Income allocated to Preferred Operating Partnership noncontrolling units and Operating Partnership and other noncontrolling units was adjusted to reflect the increase in net income resulting from the acquisitions and other pro forma adjustments as follows:

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ESS PRISA III LLC

Financial Statements and Report of Independent Auditors

For the Years ended December 31, 2011, 2010 and 2009

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Report of Independent Auditors

To the Members of

ESS PRISA III LLC

We have audited the accompanying balance sheets of ESS PRISA III LLC as of December 31, 2011, 2010, and 2009, and the related statements of operations, members’ equity, and cash flows for the years then ended.  These financial statements are the responsibility of the management of ESS PRISA III LLC.  Our responsibility is to express an opinion on this financial statement based on our audits.

We conducted our audits in accordance with auditing standards generally accepted in the United States.  Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement.  We were not engaged to perform an audit of ESS PRISA III LLC’s internal control over financial reporting. Our audit included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of ESS PRISA III LLC’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statement, assessing the basis of accounting used and significant estimates made by management, and evaluating the overall financial statement presentation.  We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in all material respects, the financial position of ESS PRISA III LLC at December 31, 2011, 2010, and 2009, and the results of its operations and its cash flows for the years then ended, in conformity with U.S. generally accepted accounting principles.

/s/ Ernst & Young LLP

Salt Lake City, Utah

April 2, 2012

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ESS PRISA III LLC

BALANCE SHEETS

(dollars in thousands)

See accompanying notes.

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ESS PRISA III LLC

STATEMENTS OF OPERATIONS

(dollars in thousands)

See accompanying notes.

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ESS PRISA III LLC

STATEMENTS OF MEMBERS’ EQUITY

(dollars in thousands)

See accompanying notes.

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ESS PRISA III LLC

STATEMENTS OF CASH FLOWS

(dollars in thousands)