Moderna crashes 18-25% as leaked cancer-vaccine Phase 3 data triggers sell-the-news retreat
What happened
Moderna shares collapsed as much as 25% on Thursday — Reuters reported a close around $183.88, down 25.2% and the stock's steepest one-day percentage fall on record — after partial results from the Phase 3 trial of its personalized melanoma vaccine intismeran autogene leaked early. The data, scheduled for a formal ESMO presentation on Saturday, appeared on the oncology site Oncology Central (later pulled) and circulated on social media; ESMO confirmed the embargo had been breached and lifted it, prompting Moderna and Merck to release the full dataset Thursday afternoon. The data showed intismeran plus Merck's Keytruda reduced the risk of recurrence or death by 42% (hazard ratio 0.58) and the risk of distant metastasis or death by 38% versus Keytruda alone in high-risk melanoma patients. Trading was briefly halted for volatility, and the selloff erased roughly $24 billion of market value. Merck, the co-developer, fell about 1-2%.
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Who’s affected
- Moderna (MRNA) — direct target of the selloff, worst performer in the S&P 500 Thursday, trading briefly halted on volatility
- Merck (MRK) — co-developer of intismeran alongside Keytruda; shares slipped ~1-2% as the partner