SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* MULLEN JAMES C (Last) (First) (Middle) 14 CAMBRIDGE CENTER (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol BIOGEN IDEC INC [ BIIB ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner X Officer (give title below) Other (specify below) CEO and President
	3. Date of Earliest Transaction (Month/Day/Year) 11/12/2003
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/12/2003		A		44,252	A	(1)	44,252	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
1985 NQ Stock Option	$7.31	11/12/2003		A		35,075		(2)	12/09/2004	Common Stock	35,075	(3)	35,075	D
1985 NQ Stock Option	$11.73	11/12/2003		A		73,600		(4)	09/22/2005	Common Stock	73,600	(3)	73,600	D
1985 NQ Stock Option	$16.9	11/12/2003		A		46,000		(5)	12/06/2006	Common Stock	46,000	(3)	46,000	D
1985 NQ Stock Option	$15.54	11/12/2003		A		46,000		(6)	12/12/2007	Common Stock	46,000	(3)	46,000	D
1985 NQ Stock Option	$35.42	11/12/2003		A		69,000		(7)	12/11/2008	Common Stock	69,000	(3)	69,000	D
1985 NQ Stock Option	$36.09	11/12/2003		A		402,500		(8)	01/04/2009	Common Stock	402,500	(3)	402,500	D
1985 NQ Stock Option	$62.28	11/12/2003		A		172,500		(9)	12/09/2009	Common Stock	172,500	(3)	172,500	D
1985 NQ Stock Option	$51.85	11/12/2003		A		287,500		(10)	06/16/2010	Common Stock	287,500	(3)	287,500	D
1985 NQ Stock Option	$45.46	11/12/2003		A		143,750		(11)	12/15/2010	Common Stock	143,750	(3)	143,750	D
1985 NQ Stock Option	$49.03	11/12/2003		A		402,500		(12)	12/14/2011	Common Stock	402,500	(3)	402,500	D
1985 NQ Stock Option	$37.45	11/12/2003		A		345,000		(13)	12/06/2012	Common Stock	345,000	(3)	345,000	D

Explanation of Responses:

1. The securities reported on this form were acquired by the reporting person in the merger of Bridges Merger Corporation, a wholly owned subsidiary of the Issuer, with and into Biogen, Inc. ("Biogen") effective on November 12, 2003 (the "Merger"). In the Merger, each share of common stock of Biogen, Inc. was exchanged for 1.15 (the "Exchange Ratio") shares of common stock of the Issuer.

2. The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 12/09/94.

3. In connection with the Merger, the Issuer assumed all options outstanding at the effective time of the merger under Biogen's existing stock option plans, including the options being reported on this form by the reporting person. Each such Biogen stock option is now exercisable for shares of the Issuer's common stock. The exercise price for each share of Issuer common stock is calculated by dividing the exercise price of the option immediately prior to the Merger for a share of Biogen common stock by the Exchange Ratio (rounded up to the nearest cent). The number of shares of Issuer common stock for which an assumed option may be exercised is calculated by multiplying the number of shares of Biogen common stock for which the option was exercisable immediately prior to the Merger by the Exchange Ratio (rounded down to the nearest whole share).

4. The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 09/22/95.

5. The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 12/06/96.

6. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/12/97.

7. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/11/98.

8. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date of 01/04/99.

9. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/09/99.

10. (10) The stock option became exercisable in seven (7) equal annual installments, commencing one year after the grant date of 06/16/00.

11. The stock option became exercisable in seven (7) equal annual installments, commencing one year after the grant date of 12/15/00.

12. The stock option became exercisable in four (4) equal annual installments, commencing one year after the grant date of 12/14/01.

13. The stock option became exercisable in four (4) equal annual installments, commencing one year after the grant date of 12/06/02.

	/s/ James C. Mullen	11/12/2003
	** Signature of Reporting Person	Date
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