PomegraModerna Stock Falls 25% After Melanoma Vaccine Data Leak
Why did Moderna stock fall 25%?
Moderna (MRNA) stock fell 25% to about $185 on Thursday after melanoma cancer vaccine data leaked online two days early, showing a result below what investors had hoped for.
Key numbers
| Moderna close | $185-24.7% from $245.81 |
|---|---|
| Recurrence or death risk | -42%vs Keytruda alone |
| Distant spread or death risk | -38%vs Keytruda alone (per [3]) |
| Cancer-free at 2 years | 82.2%vs 70% on Keytruda alone (per [2]) |
| Merck move | -3.9% intradaylater -1.7% at $147.30; sources differ |
| Earlier trial benefit | 44%–49%reports differ [3][4] |
What happened
Moderna (MRNA) stock fell 25% to about $185 on Thursday after melanoma cancer vaccine data leaked online two days early, showing a result below what investors had hoped for. The results were meant to be shown at a major cancer conference in Madrid (ESMO) on Saturday, but details spread on social media first. The shot, given with Merck's cancer drug Keytruda, cut the risk of the cancer returning or death by 42% compared with Keytruda alone. Analysts had hoped for 40% to 50%, and an earlier, smaller study looked stronger. Merck (MRK) shares fell as much as 3.9%.
Why it matters
Moderna's personalized cancer vaccine, a shot made for each patient's tumor, helped push its shares to more than five times their start-of-year level before this drop. The result still beat the 35% cut the company had called meaningful, so the treatment looks effective. The fall shows that even good news can hurt a stock when investors expected an almost perfect result.
Who this affects
- MarketbearishLow impact
- Biotech investors lost ground; the biotech ETF fell about 2%.
- CompanybearishHigh impact
- Moderna holders lost about a quarter of their stake's value.
- CompetitorsmixedLow impact
- BioNTech dipped about 2%; Pfizer edged up 0.9%.
- IndustrybullishMedium impact
- Late-stage win backs personalized cancer vaccines as a treatment.
Moderna vs BioNTech, Pfizer, Merck
How we got here
Moderna and Merck announce positive melanoma trial results without detailed figures.
Detailed results surface online around midday ET; Moderna shares plunge.
Moderna closes near $185, down about 25% from $245.81.
What to watch
- Official ESMO presentation in Madrid with full data, including safety results.2026-10-24
- Whether Moderna shares steady when US markets reopen after the leak-driven drop.2026-10-23
Educational content only. Not investment advice.
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