X0202 4 2006-05-25 0 0000813347 KOMAG INC /DE/ KOMG 0001230579 TAN THIAN H 1710 AUTOMATION PARKWAY SAN JOSE CA 95131 1 1 0 0 CEO Common Stock 2006-05-25 4 M 0 12500 6.48 A 153450 D Common Stock 2006-05-25 4 M 0 10000 13.16 A 163450 D Common Stock 2006-05-25 4 M 0 5000 18.85 A 168450 D Common Stock 2006-05-25 4 S 0 100 42.55 D 168350 D Common Stock 2006-05-25 4 S 0 75 42.60 D 168275 D Common Stock 2006-05-25 4 S 0 100 42.62 D 168175 D Common Stock 2006-05-25 4 S 0 75 42.64 D 168100 D Common Stock 2006-05-25 4 S 0 75 42.66 D 168025 D Common Stock 2006-05-25 4 S 0 76 42.68 D 167949 D Common Stock 2006-05-25 4 S 0 188 42.69 D 167761 D Common Stock 2006-05-25 4 S 0 226 42.70 D 167535 D Common Stock 2006-05-25 4 S 0 138 42.71 D 167397 D Common Stock 2006-05-25 4 S 0 225 42.73 D 167172 D Common Stock 2006-05-25 4 S 0 75 42.75 D 167097 D Common Stock 2006-05-25 4 S 0 100 42.76 D 166997 D Common Stock 2006-05-25 4 S 0 175 42.79 D 166822 D Common Stock 2006-05-25 4 S 0 150 42.81 D 166672 D Common Stock 2006-05-25 4 S 0 188 42.82 D 166484 D Common Stock 2006-05-25 4 S 0 301 42.83 D 166183 D Common Stock 2006-05-25 4 S 0 404 42.84 D 165779 D Common Stock 2006-05-25 4 S 0 469 42.85 D 165310 D Common Stock 2006-05-25 4 S 0 365 42.86 D 164945 D Common Stock 2006-05-25 4 S 0 375 42.87 D 164570 D Common Stock 2006-05-25 4 S 0 150 42.88 D 164420 D Common Stock 2006-05-25 4 S 0 178 42.89 D 164242 D Common Stock 2006-05-25 4 S 0 150 42.90 D 164092 D Common Stock 2006-05-25 4 S 0 550 42.91 D 163542 D Common Stock 2006-05-25 4 S 0 297 42.92 D 163245 D Common Stock 2006-05-25 4 S 0 175 42.93 D 163070 D Common Stock 2006-05-25 4 S 0 100 42.94 D 162970 D Non-Qualified Stock Option (right to buy) 6.48 2006-05-25 4 M 0 12500 0.00 D 2013-03-17 Common Stock 12500 23000 D Non-Qualified Stock Option (right to buy) 13.16 2006-05-25 4 M 0 10000 0.00 D 2013-07-25 Common Stock 10000 25000 D Non-Qualified Stock Option (right to buy) 18.85 2006-05-25 4 M 0 5000 0.00 D 2014-03-15 Common Stock 5000 25000 D This trade was executed pursuant to a Rule 10b5-1 trading plan. The Reporting Person exercised 12,500 shares of the 100,000 share option granted on 03/17/2003, of which 25,000 shares subject to the Option shall vest on 10/07/2003 and 1/36 of the remaining 75,000 shares subject to the Option shall vest on the 7th 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. The Reporting Person exercised 10,000 shares of the 50,000 share option granted on 07/25/2003, of which 12,500 shares subject to the Option shall vest on 10/07/2003 and 1/36 of the remaining 37,500 shares subject to the Option shall vest on the 7th 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. The Reporting Person exercised 5,000 shares of the 37,500 share option granted on 03/15/2004, of which 9,375 shares subject to the Option shall vest on 03/15/2005 and 1/36 of the remaining 28,125 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. Form 4 Filing 1 of 5 (continuation report): Related transactions effected by the Reporting Person on 05/25/2006 are reported on additional Form 4s. /s/ Jan Schwartz, Attorney-in-fact for Thian Hoo Tan 2006-05-26