Sec Form 4 Filing - DENNER ALEXANDER J @ ARIAD PHARMACEUTICALS INC - 2017-02-16

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, 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 2. Issuer Name and Ticker or Trading Symbol ARIAD PHARMACEUTICALS INC [ ARIA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SARISSA CAPITAL MANAGEMENT LP, 660 STEAMBOAT ROAD 3. Date of Earliest Transaction (MM/DD/YY) 02/16/2017 (Street) GREENWICH, CT06830 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 02/16/2017 D 53,173 D 0 D Common Stock 02/16/2017 D 7,798,665 D 0 I Sarissa Capital Domestic Fund LP ( 3 ) Common Stock 02/16/2017 D 5,051,335 D 0 I Sarissa Capital Offshore Master Fund LP ( 3 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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 Stock Option (Right to Buy) $ 8.73 02/16/2017 D 75,000 ( 4 ) ( 4 ) Common Stock 75,000 $ 0 0 D Stock Option (Right to Buy) $ 6.45 02/16/2017 D 25,000 ( 4 ) ( 4 ) Common Stock 25,000 $ 0 0 D Stock Option (Right to Buy) $ 4.91 02/16/2017 D 25,000 ( 4 ) ( 4 ) Common Stock 25,000 $ 0 0 D Stock Option (Right to Buy) $ 23.82 02/16/2017 D 25,000 ( 4 ) ( 4 ) Common Stock 25,000 $ 0 0 D 3.625% Convertible Notes due 2019 $ 9.3015 02/16/2017 D 5,340,720 ( 5 ) ( 5 ) Common Stock 5,340,720 $ 0 0 I Sarissa Capital Domestic Fund LP ( 3 ) 3.625% Convertible Notes due 2019 $ 9.3015 02/16/2017 D 3,459,280 ( 5 ) ( 5 ) Common Stock 3,459,280 $ 0 0 I Sarissa Capital Offshore Master Fund LP ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other DENNER ALEXANDER J C/O SARISSA CAPITAL MANAGEMENT LP 660 STEAMBOAT ROAD GREENWICH, CT06830 X Signatures /s/ Alexander J. Denner, Ph.D. 02/16/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the Agreement and Plan of Merger, dated as of January 8, 2017 (the "Merger Agreement"), between the Company, Takeda Pharmaceutical Company Limited ("Takeda") and Kiku Merger Co., Inc. ("Purchaser"), on February 16, 2017, Merger Sub was merged with and into the Company, with the Company continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). Pursuant to the Merger Agreement, at the effective time of the Merger, each share of common stock, par value $0.001 per share, of the Company (each, a "Share") was converted into the right to receive $24.00 in cash. ( 2 )The number of Shares reported includes 5,508 unvested restricted Shares subject to a lapsing right of repurchase by the Company (each, a "Restricted Share") and 12,500 Shares underlying unvested restricted stock units (each, an "RSU"). By virtue of the Merger and without any required action on the part of the holder thereof, all vesting conditions and restrictions applicable to each Restricted Share lapsed and each Restricted Share was converted automatically into the right to receive $24.00 in cash. In addition, pursuant to the Merger Agreement, each RSU outstanding immediately prior to the consummation of the Merger automatically and without any required action on the part of its holder became fully vested and was converted immediately prior to, and contingent upon, the consummation of the Merger into a vested right to receive a lump-sum cash payment in an amount equal to $24.00 for each Share underlying the RSU, less any required withholding taxes. ( 3 )The reporting person is the Chief Investment Officer of Sarissa Capital Management LP, investment manager of this fund. As such, the reporting person may be deemed to beneficially own the securities owned by this fund. The reporting person disclaims any beneficial ownership of these securities, except to the extent of his pecuniary interest therein. ( 4 )Pursuant to the Merger Agreement, each option outstanding immediately prior to the consummation of the tender offer by Takeda and Purchaser to acquire all the outstanding Shares for $24.00 in cash (the "Offer"), whether vested or unvested, automatically became fully vested and was canceled as of immediately prior to, and contingent upon, the consummation of the Offer in exchange for the right to receive a lump-sum cash payment in the amount of the Option Consideration, if any, less any required withholding taxes, with respect to such Option. "Option Consideration" means, with respect to any Option, an amount equal to the product of (i) the number of Shares issuable under such Option multiplied by (ii) the excess of (x) $24.00 over (y) the exercise price payable in respect of each Share issuable under such Option; provided, however, that the Option Consideration for each Option with an exercise price equal to or greater than $24.00 shall be $0. ( 5 )The reporting person is an indirect beneficial owner of the reported number of 3.635% Convertible Senior Notes due 2019 (the "Convertible Notes"). Following the consummation of the Merger, the Convertible Notes are solely convertible into $2,580.228 in cash (without interest) per $1,000 principal amount of Notes. However, if any of the Convertible Notes are converted on or after the date the Issuer gives notice of the occurrence of the Effective Date (as defined in the Indenture, dated as of June 17, 2014, between the Issuer and Wells Fargo Bank, National Association, a national banking association, as trustee (the "Indenture")) applicable to the Merger, and on or prior to 5:00 p.m. New York City time on the business day immediately prior to the Fundamental Change Repurchase Date (as defined in the Indenture) applicable to the Merger, the reporting person shall be entitled to receive, upon conversion, $2,592.0216 (without interest) per $1,000 principal amount of Convertible Notes.

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