X0202 4 2007-05-15 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 2007-05-15 4 S 0 100 32.40 D 311981 D Common Stock 2007-05-15 4 S 0 100 32.41 D 311881 D Common Stock 2007-05-15 4 S 0 200 32.42 D 311681 D Common Stock 2007-05-15 4 S 0 500 32.43 D 311181 D Common Stock 2007-05-15 4 S 0 300 32.44 D 310881 D Common Stock 2007-05-15 4 S 0 400 32.45 D 310481 D Common Stock 2007-05-15 4 S 0 400 32.46 D 310081 D Common Stock 2007-05-15 4 S 0 100 32.47 D 309981 D Common Stock 2007-05-15 4 S 0 100 32.48 D 309881 D Common Stock 2007-05-15 4 S 0 100 32.50 D 309781 D Common Stock 2007-05-15 4 S 0 200 32.51 D 309581 D Common Stock 2007-05-15 4 S 0 500 32.52 D 309081 D Common Stock 2007-05-15 4 S 0 600 32.53 D 308481 D Common Stock 2007-05-15 4 S 0 100 32.54 D 308381 D Common Stock 2007-05-15 4 S 0 100 32.57 D 308281 D Common Stock 2007-05-15 4 S 0 200 32.58 D 308081 D Common Stock 2007-05-15 4 S 0 700 32.59 D 307381 D Common Stock 2007-05-15 4 S 0 100 32.60 D 307281 D Common Stock 2007-05-15 4 S 0 400 32.61 D 306881 D Common Stock 2007-05-15 4 S 0 100 32.62 D 306781 D Common Stock 2007-05-15 4 S 0 300 32.63 D 306481 D Common Stock 2007-05-15 4 S 0 100 32.65 D 306381 D Common Stock 2007-05-15 4 S 0 400 32.66 D 305981 D Common Stock 2007-05-15 4 S 0 300 32.68 D 305681 D Common Stock 2007-05-15 4 S 0 200 32.69 D 305481 D Common Stock 2007-05-15 4 S 0 300 32.70 D 305181 D Common Stock 2007-05-15 4 S 0 192 32.71 D 304989 D Common Stock 2007-05-15 4 S 0 608 32.72 D 304381 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. 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 2007-05-17