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 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 * Ridgeback Capital Investments L.P.   2. Issuer Name and Ticker or Trading Symbol IRONWOOD PHARMACEUTICALS INC [IRWD] 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) 430 PARK AVENUE, 12TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 02/02/2012 (Street) NEW YORK, NY 10022 4. If Amendment, Date 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 (City) (State) (Zip) 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 Class B Common Stock (2) 02/02/2012   S   3,300 D $ 15.03 (3) 6,952,017 D (1)   Class B Common Stock (2) 02/03/2012   S   61,949 D $ 14.92 (4) 6,890,068 D (1)   Class B Common Stock (2) 02/06/2012   S   47,229 D $ 14.8 (5) 6,842,839 D (1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 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
Ridgeback Capital Investments L.P. 430 PARK AVENUE 12TH FLOOR NEW YORK, NY 10022		X
Ridgeback Capital Investments Ltd. 430 PARK AVENUE 12TH FLOOR NEW YOR,, NY 10022		X
Ridgeback Capital Management LP 430 PARK AVENUE 12TH FLOOR NEW YORK, NY 10022		X

Signatures

/s/ Bud Holman, Attorney-in-Fact		02/09/2012
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	Ridgeback Capital Investments L.P. owns all of the securities reported herein directly. Ridgeback Capital Investments Ltd. is the general partner of Ridgeback Capital Investments L.P. Pursuant to an investment management agreement, Ridgeback Capital Management LP maintains investment and voting power with respect to the securities held or controlled by Ridgeback Capital Investments Ltd. Wayne Holman, an individual, controls Ridgeback Capital Management LP. Ridgeback Capital Management LP, Ridgeback Capital Investments Ltd. and Wayne Holman do not own any securities reported herein directly and disclaim beneficial ownership of any of the securities covered by this statement, except to the extent of any pecuniary interest therein.
(2)	Shares of Class B Common Stock are convertible at any time, at the holder's election, and automatically upon transfer, on a one-for-one basis into shares of Class A Common Stock.
(3)	Constitutes the weighted average purchase price for multiple transactions reported on this line having prices per share ranging from $15.00 to $15.10. The Reporting Persons will provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding each separate transaction.
(4)	Constitutes the weighted average purchase price for multiple transactions reported on this line having prices per share ranging from $14.75 to $15.01. The Reporting Persons will provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding each separate transaction.
(5)	Constitutes the weighted average purchase price for multiple transactions reported on this line having prices per share ranging from $14.63 to $14.93. The Reporting Persons will provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding each separate transaction.

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