X0202 4 2007-07-10 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 2007-07-10 4 S 0 300 39.48 D 306231 D Common Stock 2007-07-10 4 S 0 100 39.485 D 306131 D Common Stock 2007-07-10 4 S 0 400 39.49 D 305731 D Common Stock 2007-07-10 4 S 0 600 39.50 D 305131 D Common Stock 2007-07-10 4 S 0 1200 39.51 D 303931 D Common Stock 2007-07-10 4 S 0 200 39.53 D 303731 D Common Stock 2007-07-10 4 S 0 200 39.54 D 303531 D Common Stock 2007-07-10 4 S 0 500 39.55 D 303031 D Common Stock 2007-07-10 4 S 0 150 39.57 D 302881 D Common Stock 2007-07-10 4 S 0 100 39.61 D 302781 D Common Stock 2007-07-10 4 S 0 101 39.63 D 302680 D Common Stock 2007-07-10 4 S 0 100 39.64 D 302580 D Common Stock 2007-07-10 4 S 0 300 39.65 D 302280 D Common Stock 50583 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 and amended on May 21, 2007. Includes 251,250 shares of restricted common stock. Due to the SEC's row number limitations this Form 4 is being filed in four parts. This is part 4 of 4 /s/ Eric D. Jacobs as attorney-in-fact for Mark F. O'Neil 2007-07-12