SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No.4)* Biogen Idec Inc. (Name of Issuer) Common Stock, Par Value $0.0005 (Title of Class of Securities) 09062X103 (CUSIP Number) Marc Weitzen, Esq. Icahn Capital LP 767 Fifth Avenue, 47th Floor New York, New York 10153 (212) 702-4388 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) May 20, 2011 (Date of Event which Requires Filing of this Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Section 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box / /. NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent. *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page. The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON High River Limited Partnership 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 2,685,803 8 SHARED VOTING POWER 0 9 SOLE DISPOSITIVE POWER 2,685,803 10 SHARED DISPOSITIVE POWER 0 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,685,803 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.11% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Hopper Investments LLC 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 2,685,803 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 2,685,803 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,685,803 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.11% 14 TYPE OF REPORTING PERSON OO SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Barberry Corp. 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 2,685,803 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 2,685,803 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,685,803 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.11% 14 TYPE OF REPORTING PERSON CO SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Partners Master Fund LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 4,441,891 8 SHARED VOTING POWER 0 9 SOLE DISPOSITIVE POWER 4,441,891 10 SHARED DISPOSITIVE POWER 0 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,441,891 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.84% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Partners Master Fund II LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 1,524,453 8 SHARED VOTING POWER 0 9 SOLE DISPOSITIVE POWER 1,524,453 10 SHARED DISPOSITIVE POWER 0 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,524,453 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.63% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Partners Master Fund III LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 662,398 8 SHARED VOTING POWER 0 9 SOLE DISPOSITIVE POWER 662,398 10 SHARED DISPOSITIVE POWER 0 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 662,398 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.27% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Offshore LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 6,628,742 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 6,628,742 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,628,742 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 2.74% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Partners LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 4,114,471 8 SHARED VOTING POWER 0 9 SOLE DISPOSITIVE POWER 4,114,471 10 SHARED DISPOSITIVE POWER 0 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,114,471 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.70% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Onshore LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 4,114,471 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 4,114,471 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,114,471 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.70% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Capital LP 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 10,743,213 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 10,743,213 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,743,213 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.45% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON IPH GP LLC 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 10,743,213 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 10,743,213 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,743,213 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.45% 14 TYPE OF REPORTING PERSON OO SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Enterprises Holdings L.P. 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 10,743,213 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 10,743,213 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,743,213 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.45% 14 TYPE OF REPORTING PERSON PN SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Icahn Enterprises G.P. Inc. 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 10,743,213 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 10,743,213 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,743,213 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.45% 14 TYPE OF REPORTING PERSON CO SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Beckton Corp. 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS WC 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 10,743,213 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 10,743,213 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 10,743,213 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.45% 14 TYPE OF REPORTING PERSON CO SCHEDULE 13D CUSIP No. 09062X103 1 NAME OF REPORTING PERSON Carl C. Icahn 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) / / (b) / / 3 SEC USE ONLY 4 SOURCE OF FUNDS 5 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) / / 6 CITIZENSHIP OR PLACE OF ORGANIZATION United States of America NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH: 7 SOLE VOTING POWER 0 8 SHARED VOTING POWER 13,429,016 9 SOLE DISPOSITIVE POWER 0 10 SHARED DISPOSITIVE POWER 13,429,016 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 13,429,016 12 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES / / 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 5.56% 14 TYPE OF REPORTING PERSON IN SCHEDULE 13D Item 1. Security and Issuer The Schedule 13D filed with the Securities and Exchange Commission on August 11, 2008 by the Reporting Persons (together with the amendments, the "Schedule 13D") with respect to the shares of Common Stock, par value $0.0005 (the "Shares"), issued by Biogen Idec Inc. (the "Issuer"), as amended by amendment number one to the Schedule 13D filed on February 6, 2009, as amended by amendment number two to the Schedule 13D filed on January 28, 2010 and as amended by amendment number three to the Schedule 13D filed on March 20, 2010, is hereby further amended to furnish the additional information set forth herein. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D. Item 3. Source and Amount of Funds or Other Consideration Item 3 of the Schedule 13D is hereby amended by replacing it in its entirety with the following: The Reporting Persons hold, in the aggregate, 13,429,016 Shares. The aggregate purchase price of the Shares currently owned by the Reporting Persons collectively was $674,668,889 (including commissions). The source of funding for the purchase of these Shares was the general working capital of the respective purchasers. The Shares are held by the Reporting Persons in margin accounts together with other securities. Such margin accounts may from time to time have debit balances. Part of the purchase price of the Shares purchased by the Reporting Persons was obtained through margin borrowing. The Shares purchased by the Reporting Persons are maintained in margin accounts that include positions in securities in addition to Shares. Item 5. Interest in Securities of the Issuer Item 5 of the Schedule 13D is hereby amended by replacing it in its entirety with the following: (a) The Reporting Persons may be deemed to beneficially own, in the aggregate, 13,429,016 Shares, representing approximately 5.56% of the Issuer's outstanding Shares (based upon the 241,632,189 Shares stated to be outstanding as of April 18, 2011 by the Issuer in the Issuer's Form 10-Q filed with the Securities and Exchange Commission for the quarterly period ended March 31, 2011). (b) High River has sole voting power and sole dispositive power with regard to 2,685,803 Shares. Each of Hopper, Barberry and Carl C. Icahn has shared voting power and shared dispositive power with regard to such Shares. Icahn Master has sole voting power and sole dispositive power with regard to 4,441,891 Shares. Each of Icahn Offshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn has shared voting power and shared dispositive power with regard to such Shares. Icahn Master II has sole voting power and sole dispositive power with regard to 1,524,453 Shares. Each of Icahn Offshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn has shared voting power and shared dispositive power with regard to such Shares. Icahn Master III has sole voting power and sole dispositive power with regard to 662,398 Shares. Each of Icahn Offshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn has shared voting power and shared dispositive power with regard to such Shares. Icahn Partners has sole voting power and sole dispositive power with regard to 4,114,471 Shares. Each of Icahn Onshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn has shared voting power and shared dispositive power with regard to such Shares. Each of Hopper, Barberry and Mr. Icahn, by virtue of their relationships to High River (as disclosed in Item 2), may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 under the Act) the Shares which High River directly beneficially owns. Each of Hopper, Barberry and Mr. Icahn disclaims beneficial ownership of such Shares for all other purposes. Each of Icahn Offshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn, by virtue of their relationships to each of Icahn Master, Icahn Master II and Icahn Master III (as disclosed in Item 2), may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 under the Act) the Shares which each of Icahn Master, Icahn Master II and Icahn Master III directly beneficially owns. Each of Icahn Offshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn disclaims beneficial ownership of such Shares for all other purposes. Each of Icahn Onshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn, by virtue of their relationships to Icahn Partners (as disclosed in Item 2), may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 under the Act) the Shares which Icahn Partners directly beneficially owns. Each of Icahn Onshore, Icahn Capital, IPH, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn disclaims beneficial ownership of such Shares for all other purposes. (c) The following table sets forth all transactions with respect to Shares effected during the past sixty (60) days by any of the Reporting Persons. Except as otherwise noted below, all such transactions were sales of Shares effected in the open market, and the table includes commissions paid in per share prices. Name of Date No. of Sale Reporting of Shares Proceeds Per Person Transaction Sold Share (US $) --------- ----------- ------ ------------ High River 04/27/2011 100,000.00 99.60 High River 04/28/2011 128,573.00 99.03 High River 04/29/2011 51,313.00 98.94 High River 05/02/2011 53,929.00 98.78 High River 05/03/2011 6,593.00 98.74 High River 05/09/2011 32,592.00 98.45 High River 05/10/2011 3,000.00 97.99 High River 05/12/2011 24,000.00 97.95 High River 05/13/2011 13,549.00 98.04 High River 05/17/2011 7,146.00 97.89 High River 05/18/2011 8,064.00 97.89 High River 05/19/2011 3,851.00 98.30 High River 05/20/2011 96,638.00 97.88 Icahn Partners 04/29/2011 2,378.00 98.94 Icahn Partners 05/02/2011 103,090.00 98.78 Icahn Partners 05/03/2011 10,763.00 98.74 Icahn Partners 05/09/2011 53,209.00 98.45 Icahn Partners 05/10/2011 4,898.00 97.99 Icahn Partners 05/12/2011 39,182.00 97.95 Icahn Partners 05/13/2011 22,120.00 98.04 Icahn Partners 05/17/2011 11,668.00 97.89 Icahn Partners 05/18/2011 13,164.00 97.89 Icahn Partners 05/19/2011 6,287.00 98.30 Icahn Partners 05/20/2011 151,617.00 97.88 Icahn Master 04/27/2011 400,000.00 99.60 Icahn Master 04/28/2011 492,942.00 99.03 Icahn Master 04/29/2011 150,474.00 98.94 Icahn Master 05/02/2011 65,690.00 98.78 Icahn Master 05/03/2011 11,620.00 98.74 Icahn Master 05/09/2011 57,444.00 98.45 Icahn Master 05/10/2011 5,287.00 97.99 Icahn Master 05/12/2011 42,300.00 97.95 Icahn Master 05/13/2011 23,882.00 98.04 Icahn Master 05/17/2011 12,595.00 97.89 Icahn Master 05/18/2011 14,212.00 97.89 Icahn Master 05/19/2011 6,787.00 98.30 Icahn Master 05/20/2011 163,683.00 97.88 Icahn Master Icahn Master II 04/28/2011 21,349.00 99.03 Icahn Master II 04/29/2011 52,402.00 98.94 Icahn Master II 05/02/2011 46,936.00 98.78 Icahn Master II 05/03/2011 3,989.00 98.74 Icahn Master II 05/09/2011 19,714.00 98.45 Icahn Master II 05/10/2011 1,815.00 97.99 Icahn Master II 05/12/2011 14,518.00 97.95 Icahn Master II 05/13/2011 8,196.00 98.04 Icahn Master II 05/17/2011 4,322.00 97.89 Icahn Master II 05/18/2011 4,878.00 97.89 Icahn Master II 05/19/2011 2,329.00 98.30 Icahn Master II 05/20/2011 56,176.00 97.88 Icahn Master III 05/20/2011 15,076.00 97.88 SIGNATURE After reasonable inquiry and to the best of each of the undersigned knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct. Dated: May 23, 2011 HIGH RIVER LIMITED PARTNERSHIP HOPPER INVESTMENTS LLC BARBERRY CORP. ICAHN PARTNERS MASTER FUND LP ICAHN PARTNERS MASTER FUND II LP ICAHN PARTNERS MASTER FUND III LP ICAHN OFFSHORE LP ICAHN PARTNERS LP ICAHN ONSHORE LP ICAHN CAPITAL LP By: IPH GP LLC, its general partner By: Icahn Enterprises Holdings L.P., its sole member By: Icahn Enterprises G.P. Inc., its general partner By: /s/ Dominick Ragone -------------------- Name: Dominick Ragone Title: Chief Financial Officer IPH GP LLC By: Icahn Enterprises Holdings L.P., its sole member By: Icahn Enterprises G.P. Inc., its general partner By: /s/ Dominick Ragone -------------------- Name: Dominick Ragone Title: Chief Financial Officer ICAHN ENTERPRISES HOLDINGS L.P. By: Icahn Enterprises G.P. Inc., its general partner By: /s/ Dominick Ragone -------------------- Name: Dominick Ragone Title: Chief Financial Officer ICAHN ENTERPRISES G.P. INC. By: /s/ Dominick Ragone -------------------- Name: Dominick Ragone Title: Chief Financial Officer BECKTON CORP. By: /s/ Edward E. Mattner ------------------------ Name: Edward E. Mattner Title: Authorized Signatory /s/ Carl C. Icahn -------------------- CARL C. ICAHN [Signature Page of Schedule 13D, Amendment No. 4 - Biogen Idec Inc.]