Moderna shares closed at $202.63 on Thursday, down 18%, after late-stage melanoma trial data leaked online ahead of their planned presentation at the European Society for Medical Oncology meeting in Madrid. The intraday decline reached 26% at its worst, marking the biggest single-day drop on record for the stock and erasing more than $17 billion in market value.
Merck confirmed the early leak from the INTerpath-001 trial, which covered 1,137 patients. The personalized cancer vaccine combined with Merck’s Keytruda cut the risk of melanoma recurrence or death by 42%. The data also showed a 38% reduction in the risk of the cancer spreading or death. After two years, 82.2% of patients receiving the combination were alive and cancer-free, compared with 70% for those on Keytruda alone, and no new safety issues were flagged.
The sell-off followed a massive rally: Moderna had nearly quadrupled from mid-August to Wednesday, closing at its highest level since December 2021. On Aug. 19, the stock jumped 177% to close at $174.38 after the company said the trial met its goals. Thursday’s decline brought the shares back toward that level, with chart support seen near $174 and the next key level near $116, where the August gap began. In premarket trading Friday, the stock was down about 3% at $195.90.
The reaction stood out against healthcare peers. Eli Lilly added more than $33 billion in market value, while Johnson & Johnson and Pfizer rose. Moderna remains up roughly 551% year to date and is now about 18% below its 52-week high of $245.81.
