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Moderna sheds about $24 billion as cancer vaccine data triggers ‘sell-the-news’ retreat

By Thomson Reuters Oct 22, 2026 | 2:54 PM

By Kamal Choudhury

Oct 22 (Reuters) – Moderna’s shares sank over 25% on Thursday as late-stage trial data for its personalized melanoma vaccine, developed with Merck, triggered what analysts called a “sell-the-news” reaction after a ​months-long stock surge.

The selloff wiped out about $24 billion from the ‌drugmaker’s market value, halting a massive rally that has lifted the stock over 500% this year.

Moderna was last down 25.2% at $183.88, set for its steepest one-day percentage fall on record, while Merck shares fell nearly 1%.

The companies, in August, reported interim data ‌that ​showed the experimental vaccine, intismeran, cut the risk ⁠of recurrence and cancer spread ⁠in high-risk melanoma patients in a late-stage trial with over 1,100 patients.

Detailed results from the trial on Thursday showed that intismeran combined with Merck’s immunotherapy Keytruda reduced the risk of cancer recurrence or death ​by 42%, while cutting the risk of distant metastasis or death by 38% compared to Keytruda alone.

Moderna and Merck released the data after ⁠the results leaked on an oncology website ⁠earlier in the day, sparking the stock fall.

‘SOLID DATA’

UBS ​analyst Michael Yee said the recurrence-free survival results are “solid data,” and that the ​pullback was an expected “‘sell the news’ event,” referring to the ‌trading strategy of buying shares when a rumor appears and selling them when it becomes a reality.

Expectations were high given the rally driven by “bullish commentary from the companies,” he said.

William Blair analyst Myles Minter described the trial ⁠data as “great” and concurred that the reversal appears to be a “sell-the-news” reaction.

But investors may now be questioning whether the treatment will prove as effective in other ⁠cancer types to justify ‌the high valuation, Minter said.

TD Cowen analysts also ⁠said the 42% recurrence reduction was “compelling” and squarely in ​the “exceptional range” ‌defined by medical experts.

Merck and Moderna said overall ​survival data ⁠are not yet mature but show a “favorable trend,” and said they are engaging with regulatory authorities.

The results, based on patient data for the first two years after treatment, are scheduled to be presented on Saturday at the European Society for Medical Oncology meeting in Madrid.

(Reporting by Kamal Choudhury in Bengaluru; Editing ​by Sahal Muhammed)