X0303 4 2009-04-29 0000789019 MICROSOFT CORP MSFT 0000902012 GATES WILLIAM H III ONE MICROSOFT WAY REDMOND WA 98052 1 0 0 0 Common Stock 2009-04-29 4 S 0 1000000 20.4601 D 752134134 D This transaction was executed in multiple trades at prices ranging from $20.23 to $20.69. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transactions were effected. In addition, there are 424,816 shares owned by the reporting person's spouse. The reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities for purposes of Section 16 or for any other purposes. (a) Duly authorized under Special Limited Power of Attorney filed on April 15, 2009 as Exhibit No. 99.2 to Amendment No. 1 of Cascade Investment, L.L.C.'s Schedule 13D with respect to Otter Tail Corporation. /s/ Alan Heuberger, Attorney-In-Fact for William H Gates III (a) 2009-05-01