Annexon proposes $75,000,000 stock offering, prices shares at $2.60

Annexon, Inc. (Nasdaq: ANNX) priced an underwritten public offering on November 12, 2025: 25,096,153 shares of common stock at $2.60 per share and, in lieu of common stock for certain investors, pre-funded warrants for 3,750,000 shares at $2.599 each, the public price less the $0.001 exercise price. The company expects gross proceeds of $75 million before underwriting discounts and other expenses, and the offering was due to close on November 14, 2025. The last reported sale price on November 11, 2025 was $2.97 per share.

The prospectus supplement gives the total public offering price as $74,996,247.80. Underwriting discounts and commissions are $0.156 per share and per pre-funded warrant, $4,499,999.87 in total, leaving $70,496,247.96 before expenses. Annexon estimates net proceeds of approximately $69.9 million, or approximately $80.4 million if the underwriters buy all of an option for up to 4,326,922 more shares, which they can exercise for 30 days.

Banks and counsel

Goldman Sachs & Co. LLC, TD Securities (USA) LLC and Wells Fargo Securities, LLC are the representatives of the underwriters. The pricing release calls Goldman Sachs & Co. LLC, TD Cowen and Wells Fargo Securities joint book-running managers and names no lead. Cooley LLP of New York passes on the validity of the securities for Annexon, and Latham & Watkins LLP of New York advises the underwriters. The company has agreed to a 60-day lock-up.

That program is a March 26, 2024 sales agreement with Cowen and Company, LLC, as sales agent, for up to $100.0 million. As of the supplement, Annexon had sold 10,490,824 shares under it, including 4,504,865 after September 30, 2025. The offering uses a Form S-3 shelf, File No. 333-278246, filed March 26, 2024 and declared effective April 1, 2024.

Dilution

Annexon had 115,122,582 shares outstanding at September 30, 2025, and 140,218,735 after the offering, assuming no exercise of the new pre-funded warrants. Net tangible book value was $161.4 million, or $1.40 per share. As adjusted for the offering it would be approximately $231.3 million, or approximately $1.61 per share, an immediate dilution of $0.99 per share to investors in the offering.

Those totals leave out 38,543,577 shares issuable on exercise of pre-funded warrants already outstanding at a weighted average exercise price of $0.001, 6,877,622 shares issuable on common warrants at a weighted average of $5.81, and 19,381,754 shares issuable on options at a weighted average of $6.64.

Use of proceeds

Annexon says it will use the net proceeds, with existing cash and cash equivalents and short-term investments, to advance tanruprubart in Guillain-Barré syndrome and vonaprument in dry age-related macular degeneration with geographic atrophy, and for working capital. It says that, on its current operating plan, the money should extend operations one year past the anticipated vonaprument topline pivotal data. The supplement states no cash balance, net loss or cash burn for any period. The company's annual report lists significant losses since inception among its main risks.

The two lead programs

Tanruprubart is aimed at Guillain-Barré syndrome, which the company says affects about 150,000 people a year, with no FDA-approved therapies. The company says that in its placebo-controlled Phase 3 trial about 90% of treated patients improved by week 1 and more than twice as many reached a normal state of health at week 26. It gives no comparison figures, and says the completed placebo-controlled studies were run in Southeast Asia. The open-label FORWARD study in the U.S. and Europe is ongoing, and dialogue with the FDA continues about the generalizability package for a biologics license application. A European marketing application is expected in January 2026.

Vonaprument targets geographic atrophy. The company says that in the Phase 2 ARCHER trial it reduced the risk of 15-letter vision loss by more than 70%. ARCHER II, a global, sham-controlled, double-masked Phase 3 trial, completed enrollment of 659 patients in July 2025, and topline data are planned for the second half of 2026.

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