BOSTON, Nov 6 (Reuters) - Ironwood Pharmaceuticals on Friday handed a board seat to Sarissa Capital Management, sparking its shares to surge as much as 14% when the activist investor secured the spot after a quiet but forceful 2-1/2-year campaign to join the group.

Alexander Denner, a widely known healthcare investor who founded Sarissa in 2013, will join Ironwood's board as its 10th director, the company said.

"His wealth of knowledge will be invaluable as we continue on our mission to advance GI (gastrointestinal) medicines, redefine the standard of care for GI patients, and deliver shareholder value," Julie McHugh, chair of Ironwood's board, said in a statement about Denner.

The company's shares were trading at $10.94, up 9%, at midday.

Ever since Sarissa, which owned 14 million shares, or roughly 9% of the Boston-based company, at the end of June, bought into Ironwood in late 2017, Denner has wanted a say in shaping its future.

Even though Ironwood's irritable bowel syndrome drug Linzess was widely prescribed, posting U.S. net sales of $803 million in 2019, the share price has languished around $10.

Certain investors grew restless and said they wanted to see a sale of the company to a larger drug company, at a time when Ironwood was already collaborating with Allergan, which was sold to AbbVie in 2020. So far, Sarissa, which has about $1.5 billion in capital, has been publicly mum on exactly what it would like beyond a higher share price.

Denner, who earned a Ph.D. in biomedical engineering from Yale and previously worked for famed investor Carl Icahn, has a reputation in the activist investing world of working collaboratively behind the scenes. He has run only one proxy contest and kept The Medicines Company founder Clive Meanwell as chief innovation officer after he was replaced as CEO.

But Denner also engineered the sales of Ariad Pharmaceuticals to Takeda and Bioverativ to Sanofi. (Reporting by Svea Herbst-Bayliss; Editing by Kirsten Donovan and Paul Simao)