UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

For the fiscal year ended December 31, 2013

OR

Commission file number 001-34456

COLONY FINANCIAL, INC.

(Exact Name of Registrant as Specified in Its Charter)

(310) 282-8820

(Registrant’s Telephone Number, Including Area Code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  x    No  ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act.    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filed, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).    Yes  ¨    No  x

The aggregate market value of voting and non-voting common equity held by non-affiliates of the registrant was approximately $1.3 billion as of the last business day of the registrant’s most recently completed second fiscal quarter based upon the price at which the common shares were last sold on that day.

As of March 27, 2014, 92,359,374 shares of the Registrant’s common stock, par value $0.01 per share, were outstanding.

EXPLANATORY NOTE

This Amendment No. 1 to Form 10-K (this “Amendment”) amends the Annual Report on Form 10-K for the fiscal year ended December 31, 2013, originally filed on February 27, 2014 (the “Original 10-K”), of Colony Financial, Inc. (the “Company”). We are filing this Amendment to amend Item 15 to include the separate financial statements of CAH Operating Partnership, L.P. (“CAH OP”) as required by Regulation S-X Rule 3-09.

Rule 3-09 of Regulation S-X provides that if an investee accounted for by the equity method meets the first or third condition of the significant subsidiary tests set forth in Rule 1-02(w), substituting 20% for 10%, separate financial statements for such investee shall be filed. Such statements are required to be audited for the years in which the investee met at least one of the significant tests. CAH OP met the significance test for the Company’s fiscal year ended December 31, 2013.

This Amendment should be read in conjunction with the Original 10-K and the Company’s other filings made with the Securities and Exchange Commission subsequent to the filing of the Original 10-K. The Original 10-K has not been amended or updated to reflect events occurring after February 27, 2014, except as specifically set forth in this Amendment.

(a)

(2) Financial Statements Schedules

The financial statements of CAH Operating Partnership, L.P. and its consolidated subsidiaries are provided as Exhibit 99.1 to this Amendment.

(3) Exhibits

The Exhibit Index attached hereto is incorporated by reference under this item.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

INDEX TO EXHIBITS

The following exhibits are included, or incorporated by reference, in this Amendment (and are numbered in accordance with Item 601 of Regulation S-K). Pursuant to Item 601(a)(2) of Regulation S-K, this exhibit index immediately precedes the exhibits.