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Exhibit 10.1

EXECUTION VERSION

AMENDMENT NO. 1 dated as of August 26, 2011 (this “Amendment”), to the Incremental Assumption Agreement dated as of March 4, 2011 (the “Incremental Agreement”), among CB RICHARD ELLIS SERVICES, INC., a Delaware corporation (the “U.S. Borrower”), CB RICHARD ELLIS LIMITED, a limited company organized under the laws of England and Wales (with company no: 3536032) (the “U.K. Borrower”), CB RICHARD ELLIS LIMITED/CB RICHARD ELLIS LIMITÉE, a corporation organized under the laws of the province of New Brunswick (the “Canadian Borrower”), CB RICHARD ELLIS PTY LTD, a company organized under the laws of Australia and registered in New South Wales (the “Australian Borrower”), CB RICHARD ELLIS LIMITED, a company organized under the laws of New Zealand (the “New Zealand Borrower” and, together with the U.S. Borrower, the U.K. Borrower, the Canadian Borrower and the Australian Borrower, the “Borrowers”), CB RICHARD ELLIS GROUP, INC., a Delaware corporation (“Holdings”), the Lenders party hereto and CREDIT SUISSE AG, as Administrative Agent.

A.        Pursuant to the Incremental Agreement, the New Incremental Term Lenders have made and have agreed to make New Incremental Term Loans to the U.S. Borrower.

B.        The U.S. Borrower has requested certain amendments to the Incremental Agreement as set forth herein.

C.        Under the Credit Agreement, the Incremental Agreement is a Loan Document (as defined therein) and may be amended with, among other things, the prior written consent of the Required Lenders.

D.        The Required Lenders are willing to make the requested amendments on and subject to the terms and conditions of this Amendment.

E.        Capitalized terms used but not defined herein shall have the meanings assigned to them in the Incremental Agreement.

Accordingly, in consideration of the mutual agreements herein contained and for other good and valuable consideration, the sufficiency and receipt of which are hereby acknowledged, the parties hereto agree as follows:

SECTION 1. Amendments.    (a) Section 1(a) of the Incremental Agreement is hereby amended by adding the following at the end thereof:

“Notwithstanding the foregoing, the definition of the term “Escrow Termination Date” set forth in paragraph (b) may be amended pursuant to an agreement or agreements in writing entered into by the Borrowers, Holdings and Lenders holding outstanding Incremental Tranche C Commitments or Incremental Tranche C Terms Loans representing more than 50% of all such Incremental Tranche C Commitments or Incremental Tranche C Terms Loans, as applicable, outstanding at such time.”

(b) Section 1(b) of the Incremental Agreement is hereby amended by adding the following terms in the proper alphabetical order therein:

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“Depository” shall mean a depository institution designated by the U.S. Borrower with the consent of the Administrative Agent (which consent shall not be unreasonably withheld).

“Escrow Account” shall mean a deposit account in the name of the U.S. Borrower, established pursuant to the Escrow Agreement and over which the Collateral Agent has exclusive dominion and control. Pending the consummation of the Acquisition to be financed with the proceeds on deposit therein (or, if earlier, the Escrow Termination Date), the Escrow Account and the proceeds on deposit therein shall serve as Collateral for the Obligations.

“Escrow Agreement” shall mean an escrow and security agreement entered into prior to the Funding Date of the Incremental Tranche C Term Loans (if such Funding Date is to occur prior to the consummation of the Acquisition to be financed with such proceeds), among the U.S. Borrower, the Administrative Agent, the Collateral Agent and the Depository, in form and substance reasonably satisfactory to the Administrative Agent.

“Escrow Termination Date” shall mean November 30, 2011.

(c) Section 2 of the Incremental Agreement is hereby amended by adding the following at the end thereof:

“In the event that the Funding Date for the Incremental Tranche C Term Loans shall have occurred but the Acquisition to be financed with the proceeds of the Incremental Tranche C Term Loans shall not have been consummated at or prior to the Escrow Termination Date, the U.S. Borrower agrees on the next Business Day following the Escrow Termination Date, to prepay the Incremental Tranche C Term Loans in full, together with all accrued and unpaid interest thereon, and the Administrative Agent is hereby authorized to apply amounts on deposit in the Escrow Account in satisfaction of such payment.”

(d) Section 6(d) of the Incremental Agreement is hereby amended by adding the following immediately prior to the end thereof:

“; provided, however, that the Incremental Tranche C Term Loans may be requested by the U.S. Borrower prior to the consummation of the Acquisition to be financed with the proceeds of such Loans so long as such proceeds are funded directly into the Escrow Account.”

SECTION 2. Representations and Warranties.    To induce the other parties hereto to enter into this Amendment, Holdings and the Borrowers represent and warrant to each of the Administrative Agent, the Collateral Agent, the Issuing Banks and the Lenders that, after giving effect to this Amendment, (a) the representations and warranties set forth in Article III of the Credit Agreement and in each other Loan Document are true and correct in all material respects on and as of the Amendment Effective Date (as defined in Section 3 below), except to the extent such representations and warranties expressly relate to an earlier date, in which case such representations and warranties shall be true and correct in all material respects as of such earlier date; and (b) on and as of the Amendment Effective Date, no Default or Event of Default has occurred and is continuing.

SECTION 3. Effectiveness.    This Amendment shall become effective as of the date set forth above on the date (the “Amendment Effective Date”) on which the Administrative Agent shall have received (a) duly executed counterparts of this Amendment which, when taken

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together, bear the signatures of the Borrowers, Holdings, the Subsidiary Guarantors and the Required Lenders, and (b) the amendment fees referred to in Section 5 below.

SECTION 4. Effect of Amendment.    Except as expressly set forth herein, this Amendment shall not by implication or otherwise limit, impair, constitute a waiver of, or otherwise affect the rights and remedies of each of the Administrative Agent, the Collateral Agent, the Issuing Banks or the Lenders under the Incremental Agreement, Credit Agreement or any other Loan Document, and shall not alter, modify, amend or in any way affect any of the terms, conditions, obligations, covenants or agreements contained in the Incremental Agreement, Credit Agreement or any other Loan Document, all of which are ratified and affirmed in all respects and shall continue in full force and effect. Nothing herein shall be deemed to entitle any Loan Party to a consent to, or a waiver, amendment, modification or other change of, any of the terms, conditions, obligations, covenants or agreements contained in the Incremental Agreement, Credit Agreement or any other Loan Document in similar or different circumstances. This Amendment shall apply and be effective only with respect to the provisions of the Incremental Agreement specifically referred to herein. After the Amendment Effective Date, any reference to the Incremental Agreement shall mean the Incremental Agreement as modified hereby. Subject to Section 1(a) of the Incremental Agreement (as amended herein), this Amendment shall constitute a “Loan Document” for all purposes of the Credit Agreement and the other Loan Documents.

SECTION 5. Amendment Fees.    In consideration of the agreements of the Lenders contained in this Amendment, Holdings and the Borrowers agree to pay to the Administrative Agent, in immediately available funds, for the account of each Lender that unconditionally delivers an executed counterpart of this Amendment at or prior to 11:00 a.m., New York time, on August 26, 2011, an amendment fee in an amount equal to 0.05% of the sum of such Lender’s Term Loans, New Incremental Term Loan Commitments and Revolving Credit Commitments (whether used or unused) at such time.

SECTION 6. Counterparts.    This Amendment may be executed in counterparts (and by different parties hereto on different counterparts), each of which shall constitute an original but all of which when taken together shall constitute a single contract. Delivery of an executed signature page to this Amendment by facsimile or other customary means of electronic transmission (e.g., “pdf”) shall be as effective as delivery of a manually signed counterpart of this Amendment.

SECTION 7. Applicable Law.    THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 8. Headings.    The headings used herein are for convenience of reference only, are not part of this Amendment and are not to affect the construction of, or to be taken into consideration in interpreting, this Amendment.

SECTION 9. Acknowledgment of Guarantors.    Each of the Guarantors hereby acknowledges receipt and notice of, and consents to the terms of, this Amendment.

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed by their respective authorized officers as of the date and year first above written.

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

Name of Lenders Signing the First Amendment

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

Name of Lenders Signing the First Amendment

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

Name of Lenders Signing the First Amendment

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]

Schedule I to

Amendment No. 1 to the

CB Richard Ellis Services Inc.

Incremental Assumption Agreement

CB HoldCo, Inc.

CB Richard Ellis Investors, Inc.

CB Richard Ellis Investors, LLC

CB Richard Ellis, Inc.

CB/TCC Holdings LLC

CB/TCC, LLC

CBRE-Profi Acquisition Corp.

CBRE Capital Markets of Texas, LP

CBRE Capital Markets, Inc.

CBRE Clarion CRA Holdings, Inc.

CBRE Clarion REI Holding, Inc.

CBRE Government Services, LLC

CBRE Loan Services, Inc.

CBRE Technical Services, LLC

CBRE/LJM Mortgage Company, LLC

Insignia/ESG Capital Corporation

The Polacheck Company, Inc.

Trammell Crow Company

Trammell Crow Services, Inc.

[Signature Page to Amendment No. 1 to the CB Richard Ellis Services Inc. Incremental Assumption Agreement]