aibioSeaport Therapeutics files for IPO, plans Nasdaq listing as SPTX
Tickers SPTX
Seaport Therapeutics filed its Form S-1 on April 10, 2026 with the share count and price range still blank. The filing shows a 2025 net loss of $74,881 thousand and a stockholders' deficit of $92,545 thousand.
Key facts
- Company
- Seaport Therapeutics, Inc. (NASDAQ: SPTX)
- News type
- Financings
- Primary source
- Seaport Therapeutics, Inc. S-1 (2026-04-10)
The offering and what is still blank
Seaport Therapeutics, Inc. filed a registration statement on Form S-1 with the SEC on April 10, 2026 for an initial public offering of its common stock. The Boston company said there has been no public market for its shares. The preliminary prospectus leaves blank the number of shares offered, the estimated price range, the size of the underwriters' option to buy additional shares, the share of the offering reserved for insiders and the closing date.
Seaport has applied to list on the Nasdaq Global Market under the symbol SPTX. It says it believes it will meet the listing standards once the offering is complete, and the offering is contingent on that listing.
Underwriters, insiders and counsel
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 manager, and it gives no underwriting discount or fee amount. Goldman Sachs & Co. LLC will run a directed share program that reserves part of the offering for directors, officers, certain employees and other associated persons.
Goodwin Procter LLP and Latham & Watkins LLP are both listed under "Copies to" on the cover. The cover does not say which firm represents the company and which represents the underwriters.
The science, as the prospectus presents it
Seaport calls itself a clinical-stage therapeutics company developing oral medicines for depression, anxiety and other neuropsychiatric disorders. Its Glyph platform is a lymphatic-targeting prodrug technology that the company says bypasses first-pass metabolism to raise oral bioavailability. Seaport was formed by PureTech Health plc in April 2024, and its earlier financial statements are carve-outs from PureTech's accounts.
The lead asset, GlyphAllo (SPT-300), is an oral prodrug of allopregnanolone for postpartum depression and major depressive disorder. 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. Seaport has started a Phase 2b trial, BUOY-1, in patients with MDD, with topline data expected in the first half of 2027.
GlyphAgo (SPT-320) is a prodrug of agomelatine. In April 2026 Seaport reported Phase 1 results showing a 6.8-fold increase in bioavailability against unmodified agomelatine in a crossover comparison, and a 9.6 to 14.5-fold increase in dose-normalized exposure in the single-ascending-dose portion. Those are measures of drug levels, not clinical benefit. The company plans a Phase 2a sleep study in generalized anxiety disorder with topline data in early 2028, and a Phase 2b trial with topline data by the end of 2028.
Use of proceeds
Seaport intends to use the net proceeds, together with existing cash, cash equivalents and investments, to advance its three named programs and fund research for additional programs. The rest would go to working capital and general corporate purposes.
The 2025 numbers
Research and development expense rose to $66,313 thousand in 2025 from $25,070 thousand in 2024. General and administrative expense fell to $20,981 thousand from $27,346 thousand. The net loss was $74,881 thousand, against $46,879 thousand, and the loss per share was $10.04, against $15.83.
The 2024 figures include $14.2 million of related-party research spending and $15.2 million of stock-based compensation in general and administrative expense, against $4.6 million in 2025.
At December 31, 2025, cash, cash equivalents and investments were $233,653 thousand, the accumulated deficit was $114,109 thousand and total stockholders' deficit was $92,545 thousand. Current liabilities were $12,782 thousand, including $9,131 thousand of accrued expenses. Series A-2 and Series B convertible preferred stock sit outside equity at $99,757 thousand and $225,571 thousand, with liquidation preferences of $100,100 thousand and $226,000 thousand.
The prospectus says the preferred stock converts into 113,921,036 common shares just before the offering closes. Common shares outstanding were 8,151,200 at December 31, 2025. Pro forma net loss per share is $0.62, a figure that depends on that conversion.
What comes next
The next dated items are the BUOY-1 topline in the first half of 2027, the GlyphAgo sleep-study topline in early 2028 and the Phase 2b topline by the end of 2028.