X0202 4 2005-10-13 0 0000813347 KOMAG INC /DE/ KOMG 0001230580 YAMASHITA TSUTOMU T 1710 AUTOMATION PARKWAY SAN JOSE CA 95131 0 1 0 0 SVP, PROCESS AND PRODUCT R&D Common Stock 2005-10-13 4 M 0 96 18.85 A 10096 D Common Stock 2005-10-13 4 S 0 35 28.441 D 10061 D Common Stock 2005-10-13 4 S 0 61 28.951 D 10000 D Non-Qualified Stock Option (right to buy) 18.85 2005-10-13 4 M 0 96 0.00 D 2014-03-15 Common Stock 96 4207 D This transaction was executed pursuant to a 10b5-1 plan that was adopted on February 11, 2005. The Reporting Person exercised 96 shares of the 6,250 share option granted on 03/15/2004, of which 1,563 shares subject to the Option shall vest on 03/15/2005 and 1/36 of the remaining 4,687 shares subject to the Option shall vest on the 15th of each month thereafter, subject to the Optionee continuing to be a Participant of Komag Incorporated Amended and Restated 2002 Qualified Stock Plan on such dates. /s/ Jan Schwartz, Attorney-in-fact for Tsutomu Yamashita 2005-10-13