X0202 4 2007-03-15 0 0001333513 DealerTrack Holdings, Inc. TRAK 0001342016 ONeil Mark F C/O DEALERTRACK HOLDINGS, INC. 1111 MARCUS AVENUE, SUITE M04 LAKE SUCCESS NY 11042 1 1 0 0 Chairman of Board, Pres. & CEO Common Stock 2007-03-15 4 S 0 100 29.23 D 321741 D Common Stock 2007-03-15 4 S 0 100 29.24 D 321641 D Common Stock 2007-03-15 4 S 0 300 29.25 D 321341 D Common Stock 2007-03-15 4 S 0 200 29.27 D 321141 D Common Stock 2007-03-15 4 S 0 300 29.28 D 320841 D Common Stock 2007-03-15 4 S 0 600 29.29 D 320241 D Common Stock 2007-03-15 4 S 0 1000 29.30 D 319241 D Common Stock 2007-03-15 4 S 0 300 29.31 D 318941 D Common Stock 2007-03-15 4 S 0 200 29.34 D 318741 D Common Stock 2007-03-15 4 S 0 300 29.36 D 318441 D Common Stock 2007-03-15 4 S 0 929 29.37 D 317512 D Common Stock 2007-03-15 4 S 0 271 29.38 D 317241 D Common Stock 2007-03-15 4 S 0 400 29.39 D 316841 D Common Stock 2007-03-15 4 S 0 200 29.40 D 316641 D Common Stock 2007-03-15 4 S 0 163 29.42 D 316478 D Common Stock 2007-03-15 4 S 0 99 29.43 D 316379 D Common Stock 2007-03-15 4 S 0 300 29.44 D 316079 D Common Stock 2007-03-15 4 S 0 300 29.47 D 315779 D Common Stock 2007-03-15 4 S 0 400 29.48 D 315379 D Common Stock 2007-03-15 4 S 0 401 29.50 D 314978 D Common Stock 2007-03-15 4 S 0 200 29.51 D 314778 D Common Stock 2007-03-15 4 S 0 400 29.52 D 314378 D Common Stock 2007-03-15 4 S 0 100 29.53 D 314278 D Common Stock 2007-03-15 4 S 0 473 29.55 D 313805 D Common Stock 2007-03-15 4 S 0 300 29.56 D 313505 D Common Stock 2007-03-15 4 S 0 200 29.58 D 313305 D Common Stock 2007-03-15 4 S 0 100 29.59 D 313205 D Common Stock 2007-03-15 4 S 0 164 29.60 D 313041 D Common Stock 51164 I By Spouse Common Stock 90686 I as Trustee for The Mark F. O'Neil Qualified Grantor Retained Annuity Trust The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 10, 2006. Includes 258,750 shares of restricted common stock. Due to the SEC's row number limitations this Form 4 is being filed in two parts. This is part 1 of 2 /s/ Eric D. Jacobs as attorney-in-fact for Mark F. O'Neil 2007-03-19