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HOWL 424B3: Acquisition

Werewolf Therapeutics

Filed with the SEC on · accession 0001140361-26-043455

HOWL filed a 424B3 (prospectus (offering)) with the SEC on Nov 12, 2026. Werewolf Therapeutics entered into a merger agreement with Ambros Therapeutics, where Ambros will merge into a subsidiary of Werewolf, with Werewolf changing its name to Ambros Therapeutics. The stock moved -0.9% by the first close after the filing.

Summary of the filing

Werewolf Therapeutics entered into a merger agreement with Ambros Therapeutics, where Ambros will merge into a subsidiary of Werewolf, with Werewolf changing its name to Ambros Therapeutics. The transaction includes a $150 million concurrent PIPE financing and a contingent value right distribution to Werewolf stockholders.

For details, click here →How to read a 424B3 →

Key details

Concurrent PIPE Financing aggregate purchase price$150.0M
Ambros equity value$500.0M
Werewolf equity value$47.5M
Minimum cash proceeds condition for PIPE financing$100.0M
Final Werewolf Net Cash assumption$26.9M
AcquirerWerewolf Therapeutics, Inc.
TargetAmbros Therapeutics, Inc.
Merger subsidiaryWave Atlantis Merger Sub, Inc.

How HOWL stock reacted

Close before

$0.99

Nov 11, 2026

First close after

-0.90%

$0.98

5 trading days

—

Since filing

-0.87%

$0.98

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Frequently asked questions

What did HOWL file with the SEC on Nov 12, 2026?

HOWL filed a 424B3 (Acquisition). Werewolf Therapeutics entered into a merger agreement with Ambros Therapeutics, where Ambros will merge into a subsidiary of Werewolf, with Werewolf changing its name to Ambros Therapeutics. The transaction includes a $150 million concurrent PIPE financing and a contingent value right distribution to Werewolf stockholders.

What does a acquisition mean for HOWL stock?

A contract important enough that investors need to know about it — a big customer contract, a loan, a merger agreement or a partnership.

How do I read a 424B3?

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 424B3 (prospectus (offering)): The final terms of an offering of shares or bonds.

How did HOWL stock react to this filing?

HOWL closed at $0.99 before the filing and $0.98 on Nov 12, 2026 (-0.90%).

Other HOWL SEC filings

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