Phase 3 results leaked Thursday ahead of Saturday’s ESMO presentation, prompting an official release from Moderna and Merck.
The vaccine-Keytruda combination reduced the risk of recurrence or death by 42% and the risk of distant metastasis or death by 38% versus Keytruda alone.
Bernstein saw a sell-the-news event, while RBC questioned commercial prospects.
Moderna’s (MRNA) cancer-vaccine rally hit a setback on Thursday as shares slid toward their worst week in three months and Mizuho analyst Jared Holz warned that extreme volatility made the stock a “do-not-trade” for many investors.
MRNA stock plunged nearly 18% to close at $202.63 on Thursday, its worst session in more than two months. Shares are down 7% for the week, putting them on track for their steepest weekly loss since late July.
Speaking to CNBC, Holz said the decline did not mean the trial results were bad.”And so, I actually don’t think the data were bad at all,” he said. “It was probably just the bar that we sort of create for ourselves on Wall Street was, you know, a little bit too high, and so shares fell.”
The analyst also pointed to Moderna’s huge daily price moves as a reason many investors might avoid trading the stock. “That’s why I think, again, for a lot of investors out there, this Moderna is a do-not-trade type of stock because it’s just so volatile,” he said.
Investors were also looking for clues about whether the treatment could work beyond melanoma, Holz said. He described a split between investors expecting broad success and those who believe melanoma was the easiest tumor type to show benefit in.
“But I’m not sure we learned anything about renal cell, and I’m not sure we learned anything about lung. So we’re just going to have to wait,” he said. Holz identified BioNTech as the other cancer-vaccine developer on his radar. However, for investors bullish on the Moderna-Merck program, he highlighted Merck.
“But Merck is actually somewhat compelling here, I think, if you’re actually bullish on the prospects,” he said.
Data Leak Jolts Moderna’s Vaccine Rally
Moderna’s selloff came after a Thursday leak of Phase 3 cancer-vaccine data ahead of Saturday’s ESMO presentation in Madrid. Merck and Moderna subsequently released the official findings for their personalized vaccine, Intismeran Autogene, combined with Keytruda.
The trial of over 1,100 patients with surgically removed high-risk melanoma showed a 42% reduction in the relative risk of recurrence or death and a 38% reduction in distant metastasis or death versus Keytruda alone. Overall-survival data is immature but showed a favorable trend, with no new safety signals reported.
The topline announcement in August, which withheld numerical results, sparked Moderna’s largest one-day percentage gain on record. Shares also hit a 52-week high of $254.48 on Wednesday ahead of the detailed data release. Earlier this month, Moderna and Merck expanded their collaboration with Tempus to support potential commercialization of the cancer vaccine, while Moderna also joined the Nasdaq-100.
The company is seeking growth beyond COVID vaccines after revenue fell to $1.9 billion in 2025 from $3.2 billion in 2024. It targets cash breakeven around 2028 and will report earnings on Nov. 6.
Analysts Weigh A ‘Sell The News’ Reaction
Bernstein called Moderna’s plunge a “sell the news event,” despite a “strong Phase 3 result and meaningful validation of Moderna’s individualized neoantigen platform.” The firm’s ‘Market Perform’ rating and $45 target imply 78% downside from current levels.
TD Cowen saw the initially leaked findings as “compelling” and within the “exceptional range” outlined by key opinion leaders, but said the benefit against distant metastasis fell short of elevated expectations. The firm said the efficacy and safety profile, if confirmed, could support broad adoption, particularly in Stage II melanoma. Its ‘Hold’ rating and $90 target imply a 56% downside.
BMO Capital Markets highlighted the unanswered question of efficacy beyond melanoma. “Investors were looking for these data to demonstrate a benefit in melanoma, but also read into efficacy in other tumors. These results are not enough to drive confidence amidst elevated expectations,” the firm said.
Meanwhile, RBC called the findings “materially less impressive” than the earlier trial and questioned the commercial opportunity. “While approval is likely, commercial success is far less certain,” the brokerage said. Wells Fargo, on the other hand, said concerns about Merck’s data “may be overdone,” adding that recurrence-free survival results exceeded investor expectations.
How Do Retail Traders Feel About MRNA And MRK?
On Stocktwits, retail sentiment was ‘bullish’ for both Moderna and Merck, with message volume ‘extremely high’ for Moderna and ‘high’ for Merck.
MRNA sentiment and message volume as of October 22 | Source: Stocktwits
One user said, “$MRNA We should all support what Moderna is doing and recognize that the results published today mark a step forward for humanity.”
Another user said, “Keytruda is THE treatment for most cancers…and right now it looks like it will be used together with mRNA vaccine. That is a huge burger.”
While MRNA stock has rocketed 587% year-to-date, MRK fell 43% over the same period.
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Deepti Sri has no position in any of the stocks mentioned in this article. StockTwits’ news team content is for informational purposes only and is not intended as investment advice. For more, see our editorial policy. This article was originally published on StockTwits.
