aibioSeaport Therapeutics prices IPO of 14,160,000 shares at $18.00
Tickers SPTX
The offering totals $254,880,000 before fees, and Seaport expects net proceeds of about $233.9 million. Entities affiliated with General Atlantic, a holder of more than 5% of the stock, have indicated interest in up to $50 million of shares, which is not binding.
Key facts
- Company
- Seaport Therapeutics, Inc. (NASDAQ: SPTX)
- News type
- Financings
- Primary source
- Seaport Therapeutics, Inc. 424B4 (2026-05-01)
The pricing and the fees
Seaport Therapeutics, Inc. priced its initial public offering at $18.00 per share, according to a final prospectus dated April 30, 2026 and filed May 1, 2026. The company is offering 14,160,000 shares of common stock, for total proceeds of $254,880,000 before fees. Underwriting discounts and commissions are $1.26 a share, or $17,841,600 in total, leaving $237,038,400 before expenses.
After discounts and estimated offering expenses, the company expects net proceeds of approximately $233.9 million, or about $269.5 million if the underwriters exercise their option in full. The option covers 2,124,000 additional shares. The shares are approved for listing on the Nasdaq Global Select Market under the symbol SPTX, with delivery expected on or about May 4, 2026.
The banks and the insiders
The cover names Goldman Sachs & Co. LLC, J.P. Morgan, Leerink Partners, Citigroup and Stifel as underwriters. It does not say which of them is lead or book-running. The cover names no legal counsel and no financial advisor.
Goldman Sachs & Co. LLC will run a directed share program for up to 5% of the offering, reserved for directors, officers, certain employees and other associated people.
The prospectus says entities affiliated with General Atlantic have indicated interest in buying up to $50 million of shares at the IPO price, on the same terms as other buyers. It also says those indications are not binding, so more, fewer or no shares may go to General Atlantic. General Atlantic is one of several existing holders of more than 5%, along with ARCH Venture Partners, Sofinnova Investments, Third Rock Ventures and the founder, PureTech. The company says it has raised $325 million in net proceeds from its investors since inception.
What the company does
Seaport calls itself a clinical-stage therapeutics company developing oral medicines for depression, anxiety and other neuropsychiatric disorders, using its Glyph platform, which it describes as a lymphatic-targeting prodrug technology.
Its lead asset, GlyphAllo (SPT-300), is an oral prodrug of allopregnanolone. The company says a Phase 2a trial showed initial proof-of-concept in healthy volunteers, not patients. The prospectus also names zuranolone, an oral synthetic analog of allopregnanolone, which met its primary endpoint in five of six MDD trials. The Phase 2b BUOY-1 trial in patients with MDD is expected to report topline data in the first half of 2027.
GlyphAgo (SPT-320) is a prodrug of agomelatine. The Phase 1 results the company reports, including a 6.8-fold increase in bioavailability against unmodified agomelatine in a crossover comparison, measure drug exposure, not clinical benefit. The prospectus also cites co-founders Daphne Zohar and Dr. Steven Paul's role at Karuna Therapeutics, which Bristol Myers Squibb acquired in March 2024 for $14 billion.
Use of proceeds and the 2025 losses
Seaport intends to use the net proceeds, with existing cash, cash equivalents and investments, to advance GlyphAllo, GlyphAgo and Glyph2BLSD and to fund research for additional programs.
Research and development expense was $66,313 thousand in 2025, up from $25,070 thousand in 2024. The net loss was $74,881 thousand, against $46,879 thousand. Net loss per share was $31.54 for 2025, against $49.72 for 2024. The 2024 figures include $14.2 million of related-party research spending.
At December 31, 2025, the accumulated deficit was $114,109 thousand and total stockholders' deficit was $92,545 thousand. Current liabilities totaled $12,782 thousand. Before the offering, the prospectus puts historical net tangible book value at a deficit of $(93.8) million, or $(38.43) per share. Series A-2 and Series B convertible preferred stock sit outside equity at $99,757 thousand and $225,571 thousand.
The preferred stock converts into 36,272,475 common shares just before the offering closes. On that basis, the prospectus shows a pro forma net loss per share of $1.94 on 38,646,460 shares.
What comes next
The next dated event in the prospectus is the BUOY-1 topline in the first half of 2027.