UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

Current Report Pursuant to

Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):

February 9, 2012

IRONWOOD PHARMACEUTICALS, INC.

(Exact Name of Registrant as Specified in Charter)

Delaware	001-34620	04-3404176
(State or Other Jurisdiction	(Commission File Number)	(IRS Employer
of Incorporation)		Identification No.)

301 Binney Street
Cambridge, Massachusetts		02142
(Address of principal executive offices)		(Zip code)

	(617) 621-7722
	(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01 Other Events

On February 9, 2012, Ironwood Pharmaceuticals, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated as representatives of the several underwriters named in Schedule 1 thereto (collectively, the “Underwriters”) related to a public offering (the “Offering”) of 5,250,000 shares of the Company’s Class A common stock, par value $0.001 par value per share, at a price to the public of $15.09 per share pursuant to a registration statement on Form S-3 (File No. 333-179430) and a related prospectus supplement. In addition, the Company granted the Underwriters an option exercisable for 30 days from the date of the Underwriting Agreement to purchase, at the public offering price less any underwriting discounts and commissions, up to an additional 787,500 shares of Class A common stock. The foregoing description of the Underwriting Agreement is qualified in its entirety by reference to the Underwriting Agreement, which is filed as Exhibit 1.1 hereto and incorporated herein by reference. J.P. Morgan Securities LLC and Merrill Lynch, Pierce, Fenner & Smith acted as lead joint bookrunning managers and Morgan Stanley & Co. LLC acted as joint bookrunning manager of the Offering. The Offering closed on February 15, 2012.

On February 9, 2012, the Company issued a press release announcing the pricing of the Offering. A copy of the Company’s press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

On February 13, 2012, the Company announced that the Underwriters exercised their option to purchase an additional 787,500 shares at a public offering price of $15.09 per share. A copy of the Company’s press release is attached hereto as Exhibit 99.2 and is incorporated herein by reference.

An opinion dated February 15, 2012 regarding the validity of the shares of Class A common stock offered in the Offering is filed as Exhibit 5.1 to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits

Exhibit No.		Description

1.1		Underwriting Agreement, dated as of February 9, 2012, by and between Ironwood Pharmaceuticals, Inc., J.P. Morgan Securities LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated as representatives of the several Underwriters named in Schedule 1 thereto.

5.1		Opinion of Ropes & Gray LLP, with respect to the validity of the Class A common stock registered.

23.1		Consent of Ropes & Gray LLP (included in Exhibit 5.1)

99.1		Press Release dated February 9, 2012, announcing the pricing of an offering of Class A common stock.

99.2		Press Release dated February 13, 2012, announcing that the Underwriters exercised their option to purchase additional shares of Class A common stock.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	IRONWOOD PHARMACEUTICALS, INC.


Dated: February 15, 2012	By:	/s/ Halley E. Gilbert
		Name: Halley E. Gilbert
		Title: Vice President, Legal Affairs and General Counsel

EXHIBIT INDEX

Exhibit No.		Description

1.1		Underwriting Agreement, dated as of February 9, 2012, by and between Ironwood Pharmaceuticals, Inc., J.P. Morgan Securities LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated as representatives of the several Underwriters named in Schedule 1 thereto.

5.1		Opinion of Ropes & Gray LLP, with respect to the validity of the Class A common stock registered.

23.1		Consent of Ropes & Gray LLP (included in Exhibit 5.1)

99.1		Press Release dated February 9, 2012, announcing the pricing of an offering of Class A common stock.

99.2		Press Release dated February 13, 2012, announcing that the Underwriters exercised their option to purchase additional shares of Class A common stock.