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Moderna Stock Falls 17% After Cancer Vaccine Data Leak
Why did Moderna stock fall 17%?
Moderna (MRNA) stock fell more than 17% on Thursday, closing near $203, after partial melanoma vaccine data leaked online and investors judged its 42% benefit short of lofty hopes.
Key numbers
| Thursday close | -17%+Intraday low about -25%; the 25% figure was not the close |
|---|---|
| Friday close | $200.10-1.25% after Thursday's drop |
| Value lost Thursday | >$17BWorst day since Aug. 20 |
| Recurrence or death risk cut | 42%vs Keytruda alone; Wall Street hoped 40-50% |
| Distant spread risk cut | 38%vs Keytruda alone |
| Monday pre-market | $188.00-6.05% (per [6]) |
What happened
Moderna (MRNA) stock fell more than 17% on Thursday, closing near $203, after partial melanoma vaccine data leaked online and investors judged its 42% benefit short of lofty hopes. The data briefly appeared on a medical news site two days before a planned cancer-conference presentation, sending shares down as much as 25% that day. The vaccine, made with Merck, cut the risk of melanoma returning or death by 42% versus Keytruda alone, near the 40% to 50% investors expected but below an earlier 49% result. Shares slipped another 1.3% on Friday to $200.10.
Why it matters
Moderna's sharp drop shows how much investors had bet on its cancer vaccine, which could help it grow beyond its infectious-disease shots. The stock had nearly quadrupled since mid-August, so even a positive result left little room for disappointment. Merck, which sells Keytruda and shares the project, fell far less, because the vaccine matters much less to its overall business.
Who this affects
- MarketneutralLow impact
- Biotech overall barely moved; Moderna holders took the hit.
- CompanybearishHigh impact
- Moderna shareholders lost over $17 billion in value Thursday.
- CompetitorsneutralLow impact
- BioNTech slipped, Pfizer little changed; effects on rivals look small.
- IndustrymixedMedium impact
- Personalized cancer vaccines stay promising, but expectations now look stretched.
Moderna vs Merck, BioNTech, Pfizer
How we got here
Merck and Moderna say Phase 3 melanoma trial met its main goals.
Partial data leaks online; Moderna closes down more than 17%, after falling as much as 25%.
Moderna slips another 1.3% to close at $200.10.
Full results scheduled for presentation at a cancer conference in Madrid.
Moderna indicated down 6.05% in pre-market trading at $188.00.
What to watch
- Whether Moderna and Merck file for regulatory approval of the vaccine with KeytrudaNot yet announced
- Analyst targets of $80-$137 sit well below Friday's $200 close2026-10-26
Educational content only. Not investment advice.
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