AMLX Rises 16.9% After Launching $350M Stock Offering

Amylyx Pharmaceuticals (Nasdaq: AMLX) shares rose 16.9% on Aug 18, 2026 after the company announced it has commenced an underwritten public offering of $350.0 million of common stock.

What Amylyx announced

Amylyx said it launched an underwritten public offering totaling $350.0 million of shares of its common stock. The company also plans to give underwriters a 30-day option to purchase up to an additional $52.5 million of shares at the public offering price per share, less underwriting discounts and commissions.

All shares in the offering are being sold by Amylyx, and the deal is subject to market and other conditions. The company noted there’s no assurance the offering will be completed, or what the final size or terms will be.

The shares are being offered under a shelf registration statement on Form S-3ASR (File No. 333-293956) that became automatically effective upon filing with the SEC on March 3, 2026. Leerink Partners, Morgan Stanley, Guggenheim Securities and LifeSci Capital are acting as joint bookrunning managers.

What it means for Amylyx

In plain English, this is Amylyx raising cash by selling more stock to the public. Because the shares are being issued by the company (not existing holders), the transaction could increase the number of shares outstanding.

Amylyx said it intends to use the net proceeds from the offering, together with existing cash, cash equivalents and marketable securities, for its planned uses, though the announcement emphasized the offering’s completion and terms are not guaranteed. The underwriters’ additional $52.5 million option also leaves room for the total raise to expand if demand supports it.

How the stock reacted

AMLX traded choppily early, then finished sharply higher on the day.

Window	Move
5 min	+0.7%
10 min	-4.9%
30 min	+4.4%
1 hour	+3.6%
end of day	+16.9%

On a market-adjusted basis, AMLX outperformed the S&P 500 ETF by +17.1% the same day.