X0303 4 2009-06-05 0001060349 GAMCO INVESTORS, INC. ET AL GBL 0001052192 CASCADE INVESTMENT LLC 2365 CARILLON POINT KIRKLAND WA 98033 0 0 1 0 0000902012 GATES WILLIAM H III ONE MICROSOFT WAY REDMOND WA 98052 0 0 1 0 Class A Common Stock 2009-06-05 4 S 0 8600 53.5934 D 17345 D This transaction was executed in multiple trades at prices ranging from $53.50 to $53.80. 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. (a) Duly authorized under Special Limited Power of Attorney filed on April 15, 2009 as Exhibit No. 99.1 to Amendment No. 1 of Cascade Investment, L.L.C.'s Schedule 13D with respect to Otter Tail Corporation. (b) 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. Cascade Investment, L.L.C. By: /s/ Alan Heuberger, Attorney-In-Fact for Michael Larson, Business Manager (a) 2009-06-09 /s/ Alan Heuberger, Attorney-In-Fact for William H. Gates III (b) 2009-06-09