EXHIBIT 10.64 FOURTH AMENDMENT TO AGREEMENT FOR PURCHASE AND SALE AND JOINT ESCROW INSTRUCTIONS ----------------------------------------------- This Fourth Amendment to Agreement of Purchase and Sale and Joint Escrow Instructions (this "Fourth Amendment") is made as of September 22, 1997 by and between Kilroy Realty, L.P., a Delaware limited partnership ("Buyer") and Mission Square Partners, a California general partnership ("Seller") with respect to the following: R E C I T A L S : - - - - - - - - A. Seller and Buyer entered into that certain Agreement of Purchase and Sale and Joint Escrow Instructions providing for the sale of 3750 University Avenue, Riverside, California as amended by that certain First Amendment, that certain Second Amendment and that certain Third Amendment to the same (collectively, the "Agreement"); B. Buyer and Seller anticipate that additional time will be required to complete Buyer's review of the Property; C. Seller and Buyer desire to amend the Agreement to provide for such additional time. NOW THEREFORE, in consideration of the mutual covenants and agreements herein contained and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Seller and Buyer hereby agree as follows: A G R E E M E N T : - - - - - - - - - 1. Notwithstanding anything in the Agreement to the contrary, the Contingency Date provided for in the Agreement is hereby extended to September 23, 1997. 2. Except as set forth in this Fourth Amendment, the provisions of the Agreement remain unmodified and in full force and effect. If any provision of this Fourth Amendment conflicts with any provision of the Agreement, the provisions of this Fourth Amendment shall prevail. 3. Any capitalized terms which are not defined in this Fourth Amendment shall have the meaning provided for in the Agreement. 4. This Fourth Amendment may be signed in counterparts, including facsimile counterparts, which, when signed by both Buyer and Seller, shall constitute a binding agreement. IN WITNESS WHEREOF, the parties have executed this Fourth Amendment as of the date first written above. "Buyer" KILROY REALTY, L.P., a Delaware limited partnership By: /s/ Tyler Rose -------------------------------- Name: Tyler Rose --------------------------- Title: S.V.P. and Treasurer -------------------------- -2- "Seller" MISSION SQUARE PARTNERS, a California general partnership By: The Betty L. Hutton Title Holding Company, Inc., (formerly known as The Betty L. Hutton Company), its general partner By: /s/ Thomas C. Parker ---------------------------------------- Name: Thomas C. Parker ----------------------------------- Title: C.E.O. ---------------------------------- By: BB&K Mission Square Partners, a California general partnership, its general partner By: ---------------------------------------- Name: ----------------------------------- Title: ---------------------------------- Acknowledgment by Escrow Holder: - ------------------------------- First American Title Insurance Company hereby acknowledges the terms of this Fourth Amendment. Dated:___________, 1997 FIRST AMERICAN TITLE INSURANCE COMPANY By: -------------------------------------------- Its Authorized Agent -3-