Alec StranahanThomas LangerNoubar AfeyanStéphane BancelMani ForooharBank of AmericaLeerink PartnersModerna, Inc.Merck & Co., Inc.

Moderna stock plunges 25% to $129 on Thursday after record 176% surge, as investors take profits on positive cancer vaccine trial results with Merck

Moderna's stock plummeted 25% to $129 on Thursday, erasing over $18 billion in market value, after a record 176% surge the previous day. Investors took profits following positive trial results for a cancer vaccine developed in partnership with Merck, which showed promise in melanoma treatment.

Forbes Forbes20 August 2026 · 21:05 UTC
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Moderna's stock experienced a dramatic decline of 25% to $129 on Thursday, following a record-setting surge of 176% the previous day, which had pushed its value above $174. This drop wiped out more than $18 billion from the company's market valuation, now at $51.5 billion.

The surge was fueled by positive results from a trial of Moderna's personalized cancer vaccine, developed in collaboration with Merck. The mRNA-based vaccine, when combined with Merck's Keytruda, showed significant promise in reducing melanoma recurrence and extending patient survival without the return of cancer.

Despite the stock's plunge, analysts remain optimistic. Bank of America analyst Alec Stranahan described the trial results as a “watershed moment,” raising his price target for Moderna from $40 to $170. However, he cautioned that further testing is needed to determine how much more effective the combined treatment is compared to Keytruda alone.

The stock's volatility has also impacted the fortunes of Moderna's co-founders. Thomas Langer saw his stake rise from $730 million to $1.7 billion after the surge, while Noubar Afeyan and CEO Stéphane Bancel also experienced significant increases in their net worth, although both saw declines on Thursday as the stock fell.

Looking ahead, Moderna and Merck are exploring additional trials for the vaccine targeting other cancers, including non-small cell lung cancer and bladder cancer.

Key Insight
“Bank of America analyst Alec Stranahan quadrupled his price target to $170 from $40, calling the results a 'watershed moment' for Moderna. The stock surge made co-founder Thomas Langer a billionaire again, raising his stake from $730 million to about $1.7 billion.”
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“Moderna’s stock retreated on Thursday following a record-setting jump a day earlier, cutting more than $18 billion from the company’s market valuation, as investors appeared to pull back after the biotech giant reported breakthrough trial results for a cancer vaccine.”
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