Investors who bet against Moderna experienced a historic one‑day loss on Wednesday as the biotech company’s shares more than doubled after data showed its personalized mRNA cancer therapy reduced the risk of skin cancer recurrence and spread in a late‑stage trial.

Stock movement and short‑seller impact

At a peak of $163 per share, Moderna’s stock later settled around $148.3. Short‑interest data from analytics firm ORTEX indicated that short sellers were on track for roughly $4.8 billion in mark‑to‑market losses, with the short interest representing about 13.5% of the company’s free‑float.

“With each shorted share now down almost $100, that is exactly the kind of pressure that can trigger a squeeze,” said Peter Hillerberg, co‑founder of ORTEX. He added that the large short base and the catalyst from the trial results could keep driving the price higher as shorts scramble to cover.

Therapy results

The therapy, developed in partnership with Merck and combined with Keytruda, showed a reduction in the risk of melanoma recurrence and metastasis in the trial. While analysts await full data, the early results have sparked optimism about the potential of personalized mRNA treatments for cancer.

Market context

Moderna, known for its COVID‑19 vaccine, has been expanding its pipeline into oncology. The recent stock rally marks one of the most dramatic single‑day gains for a large‑cap biotech, highlighting investor interest in innovative cancer therapies.

For investors, the episode underscores the risk of short positions in volatile biotech stocks, especially when new clinical data can dramatically shift market sentiment.

Original reporting: Appleton, WI News Feed (HLL/CB) — read the source article.