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
X	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* VENROCK ASSOCIATES (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVENUE (Street) PALO ALTO CA 94304 (City) (State) (Zip)	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)
	3. Date of Earliest Transaction (Month/Day/Year) 03/15/2013
	4. If Amendment, Date of 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

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	03/15/2013		J(1)(2)		639,901	D	$0	1,919,704	D
Class B Common Stock	03/15/2013		J(1)(3)		920,832	D	$0	2,762,497	D
Class B Common Stock								48,387(4)	D
Class B Common Stock								40,000(5)	D
Class A Common Stock								2,442(6)	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

1. Name and Address of Reporting Person* VENROCK ASSOCIATES (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVENUE (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VENROCK ASSOCIATES II LP (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVENUE (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VENROCK ENTERPRENEURS FUND LP (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVENUE (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VR Management LLC (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVENUE (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Each share of Class B Common Stock is convertible at any time at the option of the holder thereof into one share of Class A Common Stock and has no expiration date. Each share of Class B Common Stock will convert automatically into one share of Class A Common Stock upon (i) any transfer, whether or not for value, (subject to certain exceptions); (ii) in the event of death of the reporting person; or (iii) the earliest of the following (A) the later of (1) the first date on which the number of shares of Class B Common Stock then outstanding represents less than 25% of the number of shares of Class B Common Stock outstanding at the closing of the Issuer's initial public offering, or (2) December 31, 2018, (B) December 31, 2038, or (C) the date agreed to in writing by the holders of at least a majority of then outstanding shares of Class B common stock.

2. On March 15, 2013, Venrock Associates distributed an aggregate of 639,901 shares of the Class A Common Stock of the issuer to its partners pro rata based on their respective interests in Venrock Associates. After the distribution, Venrock Associates held an aggregate of 1,919,704 shares of Class B Common Stock of the issuer.

3. On March 15, 2013, Venrock Associates II, L.P. distributed an aggregate of 920,832 shares of the Class A Common Stock of the issuer to its partners pro rata based on their respective interests in Venrock Associates II, L.P. After the distribution, Venrock Associates II, L.P. held an aggregate of 2,762,497 shares of Class B Common Stock of the issuer.

4. Consists of 48,387 shares of Class B Common Stock of the issuer held by Venrock Entrepreneurs Fund, L.P.

5. Consists of 40,000 shares of Class B Common Stock of the issuer held by VR Managment, LLC.

6. Consists of 2,442 shares of Class A Common Stock of the issuer held by VR Managment, LLC.

Remarks:

Part 1 of 2 of the Form 4 filings made by the Venrock funds on March 19, 2013 in connection with the distribution by the Venrock funds on March 15, 2013.

	/s/ David L. Stepp, Authorized Signatory	03/19/2013
	** Signature of Reporting Person	Date
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).
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