Psychiatry Drugmaker Seaport Seeks $212.4 Million in US IPO

(Bloomberg) -- Seaport Therapeutics Inc., a clinical-stage biotechnology company focused on antidepressants and anxiety drugs, is seeking to raise $212.4 million in a US initial public offering.

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The Boston-based company plans to market 11.8 million shares for $16 to $18 each, according to its filing Monday with the US Securities and Exchange Commission. At the top of that range, the biotech would have a market value of $912 million based on the outstanding shares listed in its filing.

The biotech’s offering is expected to price April 30, according to a marketing presentation.

Seaport expects to release second phase trial results for its lead drug, a treatment for major depressive disorder, in the first half of 2027. Earlier this month, the company reported positive data from an early-stage trial of its second candidate, an oral drug to treat generalized anxiety disorder, and revealed plans to advance the drug to two parallel trials.

The company, which is backed by PureTech Health Plc, had a net loss of $74.9 million last year, compared with a net loss of $46.9 million a year earlier, according to an earlier filing.

Nasdaq and London Stock Exchange-listed PureTech owns nearly 50% of Seaport after bringing in outside investors as part of funding rounds that have raised $325 million since the offshoot was founded in 2024. Those investors include affiliates of Arch Ventures Partners, which now hold 13.4%, and General Atlantic, which owns 8.6%, the filing shows.

Seaport’s Chief Executive Officer Daphne Zohar was previously the co-founder of Karuna Therapeutics. That company was acquired for $14 billion by Bristol-Myers Squibb Co. in 2024.

The offering is being led by Goldman Sachs Group Inc., JPMorgan Chase & Co., Leerink Partners, Citigroup Inc. and Stifel Financial Corp. The company plans for its shares to trade on the Nasdaq Global Market under the symbol SPTX.

(Adds pricing timeline in third paragraph. A previous version of this story corrected Zohar’s title at Karuna.)

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