X0202 3 2006-05-02 0 0000765258 IMCLONE SYSTEMS INC IMCL 0001361754 Denner Alexander J C/O VIKING GLOBAL PERFORMANCE LLC 55 RAILROAD AVENUE GREENWICH CT 06830 1 0 0 0 0001132625 VIKING GLOBAL PERFORMANCE LLC 55 RAILROAD AVENUE 3RD FLOOR GREENWICH CT 06830 1 0 0 0 Common Stock ("Common Stock") 3232000 I See footnote In addition to being a Director to the Company, Alexander J. Denner ("Mr. Denner") also serves as a portfolio manager for Viking Global Performance LLC ("VGP") which acts as (i) the general partner of Viking Global Equities LP, a Delaware limited partnership ("VGE"), and (ii) as investment manager to VGE III Portfolio Ltd., a Cayman Islands company ("VGE III"). This statement relates to the shares of Common Stock directly owned by VGE and VGE III. As general partner and investment manager, respectively, VGP has the power to dispose of and vote the shares of Common Stock directly owned by VGE and VGE III. O. Andreas Halvorsen and David C. Ott are the managing members of VGP. None of Messrs. Denner, Halvorsen, Ott or VGP directly own any shares of Common Stock. /s/ Alexander J. Denner 2006-05-05