Exhibit 10.1

STOCK PURCHASE AGREEMENT

This STOCK PURCHASE AGREEMENT (this “Agreement”) is made and entered into as of September 23, 2009, by and among Colony Financial, Inc., a Maryland corporation (the “Company”), and the undersigned Investor (the “Investor”).

WHEREAS, the Investor has a substantive, pre-existing relationship with the Company;

WHEREAS, the Company has filed a registration statement on Form S-11 (the “Registration Statement”) with the Securities and Exchange Commission (“SEC”), in connection with the Company’s proposed initial public offering (the “IPO”) of shares of the Company’s common stock, par value $0.01 per share (the “Common Stock”);

WHEREAS, concurrently with the completion of the IPO, the Company desires to issue and sell to the Investor, and the Investor desires to purchase from the Company in a private placement, upon the terms and conditions set forth in this Agreement, such number of shares of the Company’s unregistered Common Stock as provided in this Agreement (the “Shares”); and

WHEREAS, such purchase and sale of the Shares shall occur concurrently with, and be conditioned on, the closing of the IPO.

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants, agreements and warranties herein contained, the parties hereby agree as follows:

Subject to the terms and conditions of this Agreement, the Company agrees to issue and sell to the Investor at the Closing, and the Investor agrees to purchase at the Closing, that number of Shares calculated by dividing the aggregate purchase price set forth opposite the Investor’s name on Exhibit A hereto (the “Purchase Price”) by the Per Share Price (rounded to the nearest whole share). The “Per Share Price” shall be equal to the Price to Public set forth on the cover page of the final prospectus relating to the IPO.

Upon the terms and subject to the satisfaction or waiver of all of the conditions to closing set forth in this Agreement, the closing (the “Closing”) of the purchase and sale of the Shares shall take place at the offices of Hogan & Hartson L.L.P., 555 Thirteenth Street, N.W., Washington, D.C. 20004, or at such other location as the Company and the Investor may mutually agree upon. The Closing shall take place concurrently with, and shall be subject to the closing of, the IPO.

(a) Deliveries by the Investor. At the Closing, the Investor shall deliver to the Company the following:

(i) the Purchase Price, by wire transfer of immediately available funds to the account designated in writing to the Investor by the Company for such purpose;

(ii) a registration rights agreement in substantially the form attached hereto as Exhibit B (the “Registration Rights Agreement”), duly executed by the Investor; and

(iii) a lock-up agreement between the Investor and the Company’s IPO underwriters (the “Underwriters”), in the form satisfactory to the Underwriters, duly executed by the Investor.

(b) Deliveries by the Company. At the Closing, the Company shall deliver to the Investor the following:

(i) a stock certificate evidencing the Shares (the “Share Certificate”) registered in the name of the Investor; and

(ii) the Registration Rights Agreement, duly executed by the Company.

The Company hereby represents and warrants to the Investor that:

The Company is a corporation duly organized, validly existing and in good standing under the laws of the State of Maryland and has all requisite corporate power and authority to own, lease and operate its assets and properties, to carry on its business as presently conducted, to execute and deliver this Agreement and to carry out the transactions contemplated hereby.

The execution, delivery and performance of this Agreement by the Company, the fulfillment of and compliance with the respective terms and provisions hereof, and the consummation of the transactions contemplated hereby have been duly and validly authorized by all necessary corporate action on the part of the Company (none of which actions have been modified or rescinded, and all of which actions are in full force and effect). When executed by the Company, this Agreement will constitute a valid and legally binding obligation of the Company, enforceable in accordance with its terms, except as may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or other similar laws relating to or affecting creditors’ rights generally or by general equitable principles.

The Shares have been duly authorized and, upon payment by the Investor of the Purchase Price and delivery by the Company to the Investor of the Share Certificate pursuant to the terms hereof, the Shares will be validly issued and fully paid and nonassessable, and the Investor will acquire good and marketable title thereto, free and clear of all mortgages, liens, pledges, charges, claims, security interests and other encumbrances (other than any restrictions created by the Investor or any restrictions created by federal or state securities laws).

The issuance and sale by the Company of the Shares does not conflict with the articles of incorporation or bylaws of the Company or any material contract by which the Company or its property is bound, or any federal or state laws or regulations or decree, ruling or judgment of any United States or state court applicable to the Company or its property.

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The Investor has a substantive, pre-existing relationship with the Company and (i) was not contacted by the Company or its representatives for the purpose of investing in any securities of the Company offered hereby through any advertisement, article, notice or any other communication published in any newspaper, magazine or similar media or broadcast over television or radio, or any seminar or meeting whose attendees were invited by any general advertising, (ii) was not identified or contacted through the marketing of the IPO, (iii) did not independently contact the Company as a result of the Registration Statement and (iv) the Shares were not offered or sold to the Investor by any form of general solicitation or general advertising.

The Investor hereby represents and warrants to the Company that:

If the Investor is a partnership, corporation, trust or other entity or association (an “Entity”), the Investor is duly organized, validly existing and in good standing under the laws of the jurisdiction of its organization or formation and has all requisite power and authority to own, lease and operate its assets and properties, to carry on its business as presently conducted, to execute and deliver this Agreement and to carry out the transactions contemplated hereby. If the Investor is a natural person, the Investor has the full and unrestricted legal capacity to execute and deliver this Agreement and to carry out the transactions contemplated hereby.

If the Investor is an Entity, the execution, delivery and performance of this Agreement by the Investor, the fulfillment of and the compliance with the respective terms and provisions hereof, and the due consummation of the transactions contemplated hereby have been duly and validly authorized by all necessary corporate or other action on the part of the Investor (none of which actions have been modified or rescinded, and all of which actions are in full force and effect). When executed by the Investor, this Agreement will constitute a valid and binding obligation of the Investor, enforceable in accordance with its terms, except as may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or other similar laws relating to or affecting creditors’ rights generally or by general equitable principles.

The purchase by the Investor of the Shares does not conflict with the organizational documents of the Investor or with any material contract by which the Investor or its property is bound, if the Investor is an Entity, or any laws or regulations or decree, ruling or judgment of any court applicable to the Investor or the Investor’s property.

The Shares to be received by the Investor will be acquired for investment for the Investor’s own account, not as a nominee or agent, and not with a view to the resale or distribution of any part thereof, and the Investor has no present intention of selling, granting any participation in, or

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otherwise distributing the same. The Investor does not have any contract, undertaking, agreement or arrangement with any person to sell, transfer or grant participations to such person or to any third person, with respect to any of the Shares to be received by the Investor.

(a) The Investor can bear the economic risk of the investment and has such knowledge and experience in financial or business matters that the Investor is capable of evaluating the merits and risks of the investment in the Shares. If the Investor is an Entity, the Investor also represents it has not been organized solely for the purpose of acquiring the Shares.

(b) The Investor has been furnished all information the Investor considers necessary or appropriate for deciding whether to purchase the Shares. The Investor has had adequate opportunity to ask questions of, and receive answers from, the officers, employees, agents, accountants and representatives of the Company regarding the business, operations, financial condition, assets and liabilities of the Company and the terms and conditions of the offering of the Shares.

The Investor understands and acknowledges that the Shares being acquired pursuant hereto are characterized as “restricted securities” under the federal securities laws inasmuch as they are being acquired from the Company in a transaction not involving a public offering and that under such laws and applicable regulations such securities may not be resold without registration under the Securities Act of 1933, as amended (the “Securities Act”), except in certain limited circumstances. The Investor is familiar with Rule 144 promulgated under the Securities Act, as presently in effect, and understands the resale limitations imposed thereby and by the Securities Act.

The Investor understands and acknowledges that the Shares, and any securities issued in respect of or in exchange for the Shares, may bear one or all of the following legends (in addition to any other legend which may be required by other arrangements between the parties hereto):

(a) “THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR APPLICABLE STATE LAWS, AND MAY NOT BE OFFERED, SOLD, ASSIGNED, PLEDGED, TRANSFERRED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT AND, IF REQUESTED BY THE COMPANY, UPON DELIVERY OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY THAT THE PROPOSED TRANSFER IS EXEMPT FROM THE SECURITIES ACT.”

(b) Any legend required by the securities laws of any state to the extent such laws are applicable to the Shares represented by the certificate so legended.

The Investor (i) has furnished true and complete information on the investor certificate attached hereto as Exhibit C (the “Investor Certificate”) and (ii) is an “accredited investor” as that term is defined in Rule 501(a) of Regulation D promulgated under the Securities Act. The Investor is aware that the Company is relying upon the representations, warranties and agreements contained in this Agreement

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and the Investor Certificate for the purpose of determining whether this transaction meets the requirements of the exemption from the registration requirements of the Securities Act and any applicable state securities laws.

The Investor has a substantive, pre-existing relationship with the Company and (i) was not contacted by the Company or its representatives for the purpose of investing in any securities of the Company offered hereby through any advertisement, article, notice or any other communication published in any newspaper, magazine or similar media or broadcast over television or radio, or any seminar or meeting whose attendees were invited by any general advertising, (ii) was not identified or contacted through the marketing of the IPO, (iii) did not independently contact the Company as a result of the Registration Statement and (iv) the Shares were not offered or sold to the Investor by any form of general solicitation or general advertising.

The Investor agrees that, except with the prior written consent of the Company, the Investor shall at all times hold in confidence and trust and not use or disclose any confidential information of the Company provided to or learned by the Investor in connection with this Agreement. Notwithstanding the foregoing, the Investor may disclose any confidential information of the Company (i) as required by any court or other governmental body, provided that the Investor provides the Company with prompt notice of such court order or requirement to the Company to enable the Company to seek a protective order or otherwise to prevent or restrict such disclosure or (ii) discussing or using such confidential information if the same hereafter is in the public domain (other than as a result of a breach of this Agreement).

(a) All notices, demands or requests provided for or permitted to be given pursuant to this Agreement must be in writing, to the following addresses:

If to the Company, to:

Colony Financial, Inc.

2450 Broadway, 6th Floor

Santa Monica, California 90404

Attention: Chief Financial Officer

Fax No.: 310-407-7430

with a copy (which shall not constitute notice) to:

Colony Financial, Inc.

2450 Broadway, 6th Floor

Santa Monica, California 90404

Attention: Joy Mallory

Fax No.: 310-407-7416

If to the Investor, to:

The address appearing on the signature page hereof.

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This Agreement and the rights granted hereunder may not be assigned by the Investor without the prior written consent of the Company. This Agreement shall be binding upon and inure to the benefit of the parties hereto and their respective heirs, personal representatives, successors and permitted assigns as provided in this Agreement.

Nothing in this Agreement, express or implied, is intended to confer upon any person, other than the parties hereto or their respective successors and permitted assigns, any rights, remedies, obligations or liabilities under or by any reason of this Agreement, except as expressly provided in this Agreement and provided that the Underwriters shall be a third party beneficiary of this Agreement.

This Agreement contains the entire agreement and understanding among the parties hereto with respect to the subject matter of this Agreement, and supersedes all prior and contemporaneous agreements, understandings, inducements and conditions, express or implied, oral or written, of any nature whatsoever with respect to the subject matter of this Agreement. The express terms of this Agreement control and supersede any course of performance and/or usage of the trade inconsistent with any of the terms of this Agreement.

This Agreement may be amended or modified only by an agreement in writing signed by both parties hereto.

No failure or delay on the part of any party in exercising any right, privilege, power, or remedy under this Agreement, and no course of dealing shall operate as a waiver of any such right, privilege, power or remedy; nor shall any single or partial exercise of any right, privilege, power or remedy under this Agreement preclude any other or further exercise of any such right, privilege, power or remedy or the exercise of any other right, privilege, power or remedy. No waiver shall be asserted against any party unless signed in writing by such party. The rights, privileges, powers and remedies available to the parties are cumulative and not exclusive of any other rights, privileges, powers or remedies provided by statute, at law, in equity or otherwise. Except as provided in this Agreement, no notice to or demand on any party in any case shall entitle such party to any other or further notice or demand in any similar or other circumstances or constitute a waiver of the right of the party giving such notice or making such demand to take any other or further action in any circumstances without notice or demand.

THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK, WITHOUT GIVING EFFECT TO THE CHOICE OF LAW RULES THEREOF. EACH OF THE PARTIES HEREBY IRREVOCABLY AGREES THAT THE COURTS OF THE STATE OF NEW YORK SHALL HAVE EXCLUSIVE JURISDICTION IN CONNECTION WITH ANY ACTIONS OR PROCEEDINGS ARISING BETWEEN THE PARTIES UNDER THIS AGREEMENT. EACH OF THE PARTIES HEREBY IRREVOCABLY CONSENTS AND SUBMITS TO THE JURISDICTION OF SAID COURTS FOR

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ANY SUCH ACTION OR PROCEEDING. EACH OF THE PARTIES HEREBY WAIVES THE DEFENSE OF AN INCONVENIENT FORUM TO THE MAINTENANCE OF ANY SUCH ACTION OR PROCEEDING IN SAID COURTS.

EACH PARTY HERETO HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES THE RIGHT TO A TRIAL BY JURY IN ANY ACTION, SUIT, COUNTERCLAIM OR OTHER PROCEEDING (WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) ARISING OUT OF, CONNECTED WITH OR RELATING TO THIS AGREEMENT, THE TRANSACTIONS CONTEMPLATED HEREBY, OR THE ACTIONS OF ANY HOLDER IN THE NEGOTIATION, ADMINISTRATION, PERFORMANCE OR ENFORCEMENT HEREOF.

The headings contained in this Agreement are for convenience only and shall not affect the construction or interpretation of any provisions of this Agreement.

If any provision of the Agreement shall be held to be invalid, the remainder of the Agreement shall not be affected thereby.

This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original as against any party whose signature appears thereon, and all of which shall together constitute one and the same instrument. This Agreement shall become binding when one or more counterparts of this Agreement, individually or taken together, shall bear the signatures of all of the parties reflected hereon as the signatories.

Signatures on following page

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IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date first written above.

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Exhibit A

Each of the following executive officers of Colony Financial, Inc. (the “Company”) have entered into a Stock Purchase Agreement with the Company in the form substantially identical in all material respects to the Stock Purchase Agreement to which this Exhibit A is attached, and such agreements differ only with respect to the total number of shares of the Company’s common stock purchased by such individuals, which is calculated by dividing the aggregate purchase price set forth opposite such individual’s name in the table below by the initial public offering price per share ($20.00).

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Exhibit B

FORM OF REGISTRATION RIGHTS AGREEMENT

(see attached)

[SEE EXHIBIT 10.2, AS FILED WITH AMENDMENT NO. 5 TO THE REGISTRATION

STATEMENT ON FORM S-11 OF COLONY FINANCIAL, INC.]

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