Sec Form 4 Filing - Senator Investment Group LP @ IDERA PHARMACEUTICALS, INC. - 2012-04-19

Insider filing report for Changes in Beneficial Ownership
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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
Senator Investment Group LP
2. Issuer Name and Ticker or Trading Symbol
IDERA PHARMACEUTICALS, INC. [ IDRA]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director X __ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last) (First) (Middle)
510 MADISON AVENUE, 28TH FLOOR
3. Date of Earliest Transaction (MM/DD/YY)
04/19/2012
(Street)
NEW YORK, NY10022
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 04/23/2012 S 91,000 D $ 1.88 2,724,700 I See Footnoes ( 1 ) ( 2 )
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
Reporting Owners
Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Senator Investment Group LP
510 MADISON AVENUE
28TH FLOOR
NEW YORK, NY10022
X
Signatures
Evan Gartenlaub, General Counsel 04/25/2012
Signature of Reporting Person Date
Explanation of Responses:
( 1 )The entities and individuals identified in this Form 4 (the "Reporting Persons") disclaim any membership in any "group".
( 2 )The amount of securities shown in this row is owned by Senator Global Opportunity Master Fund L.P. (the "Master Fund"). As Investment Manager to the Master Fund, Senator Investment Group LP ("Senator LP") may be deemed to be the beneficial owner of the Issuer's securities owned by the Master Fund, but disclaims beneficial ownership to the extent such ownership exceeds its pecuniary interest. Douglas Silverman, a United States citizen, and Alexander Klabin, a United States citizen, have control of a Delaware limited liability company that may be deemed to control Senator LP. Each of Messrs. Silverman and Klabin disclaim beneficial ownership of the shares held by the Master Fund to the extent such beneficial interest exceeds his pecuniary interest.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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