Moderna’s dip came from good news that was not good enough. On Thursday, October 22, screenshots of Phase 3 results for intismeran autogene, the personalized melanoma vaccine Moderna is developing with Merck, began circulating on social media two days before their scheduled presentation, according to Biopharma Dive. The European Society for Medical Oncology then released the full study details early. Moderna’s shares fell as much as 25% during the session, CNBC reported, and ended the day down about 18%, according to Yahoo Finance. Merck slipped about 1%.

Reuters, in a report published by Investing.com, put the loss in market value at about $24 billion when the shares were down 25%. At the close, the loss works out to roughly $17 billion by Lens’s arithmetic.

The data were positive

Added to Merck’s immunotherapy Keytruda, the vaccine cut the risk of melanoma returning or death by 42% compared with Keytruda alone, and the risk of distant spread or death by 38%, in a late-stage trial of more than 1,100 patients with high-risk melanoma. At two years, 82% of patients on the combination were alive without their cancer returning, against 70% on Keytruda alone, CNBC reported. A separate analysis of the six-month regimen showed a 58% reduction in recurrence or death. Overall survival data are not yet mature, though the companies describe a favorable trend.

Side effects were broadly similar, according to Biopharma Dive, with more fever and injection-site pain among vaccine recipients. About 7% stopped treatment because of adverse events, against 5% in the comparison group. Moderna chief executive Stéphane Bancel called it “a very, very happy moment for the field, for patients,” and told CNBC that the company is finishing a regulatory filing for full approval. Merck chief executive Robert Davis said the company believes it can shorten the roughly six-week manufacturing timeline.

The problem was expectations

Investors had expected a reduction of 40% to 50%, Biopharma Dive reported, even though Moderna had said 35% would be clinically significant. Their anchor was the smaller mid-stage trial, which showed a 44% reduction at its first analysis and about 49% at five years. The two trials are not directly comparable, since they differ in size and length of follow-up, but the earlier figure was the best number the market had.

The bigger issue was price. Moderna’s shares had risen more than 500% this year before the drop, according to Reuters. Yahoo Finance calculated that the stock traded at about 52 times forward sales going into the selloff, against a five-year average of 7.7 times. After the fall, the multiple was closer to 38 times, still about five times its historical norm.

Bar chart on a black background: Moderna's forward price-to-sales multiple was about 52x before the October 22, 2026 drop and about 38x after, against a five-year average of 7.7x.
Moderna’s forward price-to-sales multiple before and after the October 22 drop, against its five-year average. Source: Yahoo Finance.

Analysts mostly blamed positioning, not the science. William Blair’s Myles Minter said a “sell-the-news reaction is playing out.” UBS’s Michael Yee called the recurrence-free survival results “solid data.” BMO’s Evan Seigerman wrote: “We assert this relative reduction in recurrence/death is clinically meaningful.” RBC’s Trung Huynh was cooler, placing the results at the “low end” of expectations. “While approval seems likely,” he wrote, “commercial success is far less certain.”

A company priced on its pipeline

The reaction was so sharp because almost all of Moderna’s value now rests on what comes next. Revenue fell from $6.85 billion in 2023 to $1.94 billion in 2025, according to Yahoo Finance, as demand for its COVID-19 vaccine faded. Moderna’s annual report put 2025 revenue 40% below 2024. The company is targeting growth of up to 10% in 2026, and the analyst consensus cited by Yahoo Finance sees $3.40 billion in 2028.

Bar chart on a black background showing Moderna's annual revenue falling from $6.85 billion in 2023 to $3.2 billion in 2024 and $1.94 billion in 2025.
Moderna’s revenue has fallen by more than two-thirds in two years as COVID-19 vaccine sales declined. Sources: Yahoo Finance and Moderna’s reported results.

That leaves the cancer pipeline carrying the valuation. Moderna and Merck are testing intismeran in lung, bladder and kidney cancer, and RBC expects interim kidney results later this year or in the first half of 2027, Biopharma Dive reported. Merck splits the vaccine’s costs and profits equally with Moderna, according to Seeking Alpha. With so little revenue underneath the share price, each data readout moves the stock hard in both directions.

Noubar Afeyan’s bet

The swing also tests the idea Moderna was built on. Noubar Afeyan, the company’s co-founder and chairman, is chief executive of Flagship Pioneering, the firm that created Moderna in 2010 on the bet that messenger RNA could become a platform for many medicines rather than a single product. The COVID-19 vaccine proved the technology at global scale. A personalized cancer vaccine, designed around the mutations in each patient’s tumor, is the clearest test yet of whether that platform can deliver a second act.

Afeyan, who was born in Beirut to an Armenian family, is also one of the most prominent figures in the Armenian diaspora. He co-founded the Aurora Humanitarian Initiative and has pushed for Armenia to become a nation that creates technology rather than only consuming it. Lens found no public comment from him on the October 22 selloff.

For Moderna’s long-term thesis, the trial result may matter more than the share price. The vaccine worked, at a level RBC expects regulators to accept, against a standard of care that is already strong. The market’s complaint was about how much of that success it had already paid for.

What to watch

  • The approval filing. Bancel says Moderna is finishing it. How US and European regulators respond will set the commercial timeline.
  • Overall survival. The companies say those data are not yet mature.
  • Kidney cancer. RBC expects interim results later this year or in the first half of 2027, the next test of whether the approach works beyond melanoma.
  • Manufacturing. Each dose is made for one patient, so Merck’s effort to shorten the six-week timeline matters for how widely the vaccine can be used.

Sources and method: Figures are as reported by CNBC, Reuters via Investing.com, Yahoo Finance, Biopharma Dive, Seeking Alpha and Moderna’s filings. The roughly $17 billion closing loss is a Lens calculation from Reuters’ intraday figure, and reports differ slightly on the exact closing decline.

Lead photo: Moderna’s office in Cambridge, Massachusetts, December 2020. Photo by Fletcher via Wikimedia Commons, licensed under CC BY 4.0.