Seres Therapeutics, Inc. (MCRB) Form S-3 — Aug 13, 2026

$MCRBForm S-3Filed Aug 13, 2026, 4:31 PM ET0001193125-26-349330Original filing

Seres Therapeutics filed a $300,000,000 universal shelf registration statement on Form S-3 on August 13, 2026, covering common stock, preferred stock, debt securities, warrants, and units. The filing includes a sales agreement prospectus supplement establishing a $100,000,000 at-the-market equity program with TD Securities (USA) LLC (TD Cowen) as sales agent. Under the ATM program, shares may be sold from time to time at prevailing market prices on the Nasdaq Global Select Market, with TD Cowen earning up to 3.0% of gross proceeds.

Key figures

Gross Proceeds: $300,000,000 total shelf capacity, including a $100,000,000 ATM program
Shares Outstanding: 10044781
Atm Program Size: $100,000,000
Rsus Outstanding: 161748
Ib6 Reference Price: $8.14 (closing price on July 7, 2026)
Atm Agent Commission: up to 3.0% of gross proceeds
Non Affiliate Shares: 7758508
Sec Registration Fee: $9,026.84
Warrants Outstanding: 32379
Net Tangible Book Value: $34.5 million, or $3.51 per share (June 30, 2026)
Last Reported Sale Price: $4.64 per share (August 11, 2026)
Non Affiliate Market Value: $63,154,255.12 (General Instruction I.B.6 calculation)
Shares Outstanding June30: 9827569
Stock Options Outstanding: 1,548,690 shares at $43.10 weighted average exercise price
Assumed Atm Shares At Full Use: 21551724
Estimated Offering Expenses: $250,000
Carried Over Unsold Securities: $234,635,462.52 from prior S-3 (No. 333-273794) under Rule 415(a)(6)
Dilution Per Share To New Investors: $0.44 (illustrative assuming full $100M sale at $4.64)
Expense Reimbursement Cap To Agent: $100,000
Adjusted Net Tangible Book Value After Atm: $131.7 million, or $4.20 per share (illustrative)

Price after filing

1 day: +1.3%7 days: +2.0%30 days: +11.8%

Close on the filing date to close N calendar days later (from $4.48). Historical, not a forecast.

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