Ironwood Pharmaceuticals Announces Adjustment of Conversion Rate for its 2.25% Convertible Senior Notes due 2020

Ironwood Pharmaceuticals, Inc. (NASDAQ: IRWD), a GI-focused healthcare company, today announced an adjustment to the conversion rate applicable to its existing 2.25% Convertible Senior Notes due 2022, effective April 15, 2019. The adjustment was effected pursuant to the indenture, dated as of June 15, 2015, and as supplemented April 5, 2019, between Ironwood and U.S. Bank National Association, as trustee, pursuant to which the Convertible Notes were originally issued.

In connection with the separation of Ironwood and Cyclerion Therapeutics, Inc. (Cyclerion) into two independent, publicly traded companies, on April 1, 2019, Ironwood distributed to its shareholders one share of Cyclerion common stock for every 10 shares of Ironwood common stock held as of the close of business on March 19, 2019, the record date for the distribution.

As a result of the separation, and pursuant to Section 4.05(c) of the indenture, effective April 15, 2019, the conversion rate under the indenture has been adjusted to equal 68.9172 shares of Ironwood Common Stock per $1,000 principal amount of the Convertible Notes.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (Nasdaq: IRWD) is a GI-focused healthcare company focused on creating medicines that make a difference for patients living with GI diseases. We discovered, developed and are commercializing linaclotide, the U.S. branded prescription market leader for adults with irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC). We are currently advancing a Phase IIIb trial evaluating the efficacy and safety of linaclotide on multiple abdominal symptoms, including bloating, pain, and discomfort, in adult patients with IBS-C.

We are also advancing two late-stage, first-in-category GI product candidates: IW-3718 is a gastric retentive formulation of a bile acid sequestrant being developed for the potential treatment of persistent gastroesophageal reflux disease, and MD-7246 is a delayed-release formulation of linaclotide that is being evaluated as an oral, intestinal, non-opioid, pain-relieving agent for patients suffering from abdominal pain associated with IBS with diarrhea.

Ironwood was founded in 1998 and is headquartered in Cambridge, Mass. For more information, please visit our newly launched website at www.ironwoodpharma.com or www.twitter.com/ironwoodpharma; information that may be important to investors will be routinely posted in both these locations.

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Media and Investors:Meredith Kaya, 617-374-5082Vice President, Investor Relations and Corporate [e-mail]