Werewolf Therapeutics stock soars on Ambros merger deal and $150 million PIPE

Werewolf Therapeutics (HOWL) is up 104.1% today. Here is some analysis on what might have caused this price movement.

Analysis: The biggest apparent catalyst is Werewolf Therapeutics’ announcement of a definitive all-stock merger agreement with private biotech Ambros Therapeutics, paired with an oversubscribed $150 million private placement. Investors appear to be reacting to the scale of the financing, the implied valuation for the combined company, and the shift toward Ambros’s late-stage lead program.

Details:

Werewolf Therapeutics and Ambros Therapeutics disclosed a merger agreement under which the combined company is expected to operate as Ambros Therapeutics and trade under the ticker AMBX.

The transaction assigns an implied value of about $500 million to Ambros Therapeutics and about $47.5 million to Werewolf Therapeutics before the concurrent financing.

The companies also announced commitments for an oversubscribed $150 million private placement, co-led by major healthcare-focused investors, with closing expected alongside the merger.

Ambros’s lead asset, neridronate for Complex Regional Pain Syndrome Type 1, is already in an ongoing Phase 3 trial, which likely strengthened investor enthusiasm compared with Werewolf’s earlier strategic review and going-concern pressure.

Sources:

SEC, Ambros Therapeutics, Investing.com

Disclaimer: This price movement analysis was generated with the help of AI. Please double-check the information provided for mistakes.

$HOWL Insider Trading Activity

$HOWL insiders have traded $HOWL stock on the open market 43 times in the past 6 months. Of those trades, 0 have been purchases and 43 have been sales.

Here’s a breakdown of recent trading of $HOWL stock by insiders over the last 6 months:

LUKE EVNIN has made 0 purchases and 29 sales selling 1,752,286 shares for an estimated $897,297.
CAPITAL MANAGEMENT, L.P. RA has made 0 purchases and 14 sales selling 1,543,973 shares for an estimated $573,245.

To track insider transactions, check out Quiver Quantitative's insider trading dashboard. You can access data on insider stock transactions through the Quiver Quantitative API insider transaction endpoint.

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$HOWL Hedge Fund Activity

We have seen 19 institutional investors add shares of $HOWL stock to their portfolio, and 30 decrease their positions in their most recent quarter.

Here are some of the largest recent moves:

RA CAPITAL MANAGEMENT, L.P. removed 4,293,563 shares (-64.3%) from their portfolio in Q2 2026, for an estimated $1,545,253
BALYASNY ASSET MANAGEMENT L.P. added 1,790,089 shares (+inf%) to their portfolio in Q2 2026, for an estimated $644,253
MPM BIOIMPACT LLC removed 1,128,668 shares (-93.4%) from their portfolio in Q2 2026, for an estimated $406,207
SQUADRON CAPITAL MANAGEMENT LLC removed 563,535 shares (-100.0%) from their portfolio in Q2 2026, for an estimated $202,816
VERDAD ADVISERS, LP added 318,949 shares (+1071.7%) to their portfolio in Q2 2026, for an estimated $114,789
XTX TOPCO LTD added 220,549 shares (+433.1%) to their portfolio in Q2 2026, for an estimated $79,375
JANE STREET GROUP, LLC added 169,001 shares (+204.0%) to their portfolio in Q2 2026, for an estimated $60,823

To track hedge funds' stock portfolios, check out Quiver Quantitative's institutional holdings dashboard. You can access data on hedge funds moves and 13F filings through the Quiver Quantitative API 13F endpoint.

This article is not financial advice. See Quiver Quantitative's disclaimers for more information. Note that there may be inaccuracies due to mistakes in ticker-mapping, and other anomalies.