SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Denner Alexander J (Last) (First) (Middle) C/O VIKING GLOBAL PERFORMANCE LLC 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 05/02/2006	3. Issuer Name and Ticker or Trading Symbol IMCLONE SYSTEMS INC [ IMCL ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock ("Common Stock")	3,232,000	I	See footnote ( 1 )

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* Denner Alexander J (Last) (First) (Middle) C/O VIKING GLOBAL PERFORMANCE LLC 55 RAILROAD AVENUE (Street) GREENWICH CT 06830 (City) (State) (Zip)

1. Name and Address of Reporting Person* VIKING GLOBAL PERFORMANCE LLC (Last) (First) (Middle) 55 RAILROAD AVENUE 3RD FLOOR (Street) GREENWICH CT 06830 (City) (State) (Zip)

Explanation of Responses:

1. 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	05/05/2006
	** Signature of Reporting Person	Date
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