Biotech
Moderna loses more than $17 billion after its melanoma vaccine data leaks early
By the newsroom · · 2 min read · ▶ 1:07
The essentials
- Moderna shares fell as much as 26% on Thursday before closing down 17.6%, at $202.63.[1][2]
- More than $17 billion in market value vanished as details from the late-stage trial circulated ahead of their official debut.[1]
- The vaccine, given with Keytruda, reduced the risk of melanoma recurrence or death by 42%, compared with Keytruda alone.[3]
- The full data is set for release Saturday, October 24, at the European Society for Medical Oncology conference in Madrid.[2][4]
What happened
Moderna stock fell as much as 26% before closing down more than 17%.[1] Shares of Moderna fell 17.6%, while Merck dropped 1.76%.[2] Moderna closed at $202.63.[5] Yahoo Finance called it the stock's biggest intraday drop on record.[1]
The figures appeared on medical news site Oncology Central around 12:30 p.m. ET and were removed shortly afterward.[4] Merck, Moderna's partner on the vaccine, confirmed the results came out early.[1] The companies then released detailed results from the phase 3 trial.[3]
The vaccine, known as intismeran autogene, reduced the risk of melanoma recurrence or death by 42% when given alongside Keytruda.[3] An earlier, smaller trial showed 49%, though it used different patients, so it isn't a direct comparison.[1] Bernstein said it was interpreting the drop "as a sell the news event."[2]
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What the video doesn't say
At two years, 82.2% of combination patients were alive and cancer-free, compared with 70% on Keytruda alone.[4] The trial enrolled roughly 1,100 patients whose tumors were removed by surgery.[3] Six melanoma specialists told CNBC the results represent a clinically meaningful advance.[3] Moderna shares are also up nearly 600% this year due to the cancer shot optimism.[3] Questions remain about whether the combination ultimately helps patients live longer.[3]
What's next?
Moderna and Merck will present the detailed results at the European Society for Medical Oncology conference on Saturday.[3] Moderna CEO Stéphane Bancel said the company is finishing a filing with regulators as it aims to get the drug fully approved next year.[3]
Sources
- 1Moderna stock crashes as leaked melanoma data threatens its record August rallyYahoo Finance · October 23, 2026
- 2Moderna stock’s 17% slump was a ‘sell the news’ event, analyst saysYahoo Finance · October 23, 2026
- 3Doctors call Moderna, Merck cancer vaccine data a major advancement - despite Wall Street reactionCNBC · October 23, 2026
- 4Moderna Stock Plunges as Apparent Leak Reveals Phase 3 Melanoma Vaccine DataYahoo Finance · October 22, 2026
- 5Stock Market Today, Oct. 22: Moderna Stock Plummets 18% on Melanoma Vaccine Data Leak Reports | The Motley FoolThe Motley Fool · October 22, 2026
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