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AMLX 424B5: Secondary offering

Filed with the SEC on · accession 0001193125-26-359416

AMLX filed a 424B5 (prospectus (offering)) with the SEC on Aug 20, 2026. Amylyx Pharmaceuticals is offering 14,090,000 shares of common stock at $35.50 per share in an underwritten public offering, with an option for underwriters to purchase an additional 2,113,500 shares. The stock moved +2.7% by the first close after the filing.

Summary of the filing

Amylyx Pharmaceuticals is offering 14,090,000 shares of common stock at $35.50 per share in an underwritten public offering, with an option for underwriters to purchase an additional 2,113,500 shares. The offering is expected to raise approximately $472.2 million in net proceeds before expenses.

For details, click here →How to read a 424B5 →

Key details

Shares offeredshares 14.1M
Public offering price per share$36
Total gross proceeds$500.2M
Underwriting discounts and commissions$28.0M
Net proceeds to company (before expenses)$472.2M
Over-allotment option sharesshares 2.1M
IssuerAmylyx Pharmaceuticals
UnderwriterLeerink Partners
UnderwriterMorgan Stanley
UnderwriterGuggenheim Securities
UnderwriterLifeSci Capital

How AMLX stock reacted

Close before

$38.60

Aug 19, 2026

First close after

+2.75%

$39.66

5 trading days

-3.94%

$37.08

Since filing

-28.45%

$27.62

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Frequently asked questions

What did AMLX file with the SEC on Aug 20, 2026?

AMLX filed a 424B5 (Secondary offering). Amylyx Pharmaceuticals is offering 14,090,000 shares of common stock at $35.50 per share in an underwritten public offering, with an option for underwriters to purchase an additional 2,113,500 shares. The offering is expected to raise approximately $472.2 million in net proceeds before expenses.

What does a secondary offering mean for AMLX stock?

New shares dilute existing holders and are often sold at a discount to the market price.

How do I read a 424B5?

The final terms of an offering of shares or bonds. Look at price, number of shares and the discount to the market price. Large offerings dilute existing shareholders.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A 424B5 (prospectus (offering)): The final terms of an offering of shares or bonds.

How did AMLX stock react to this filing?

AMLX closed at $38.60 before the filing and $39.66 on Aug 20, 2026 (+2.75%). Five trading days later: $37.08 (-3.94%).

Other AMLX SEC filings

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