Moderna Stock Plunges 25%—Wiping Out $18 Billion After Historic Cancer Vaccine Breakthrough

BreakingBusinessModerna Stock Plunges 25%—Wiping Out $18 Billion After Historic Cancer Vaccine BreakthroughByTy Roush,Forbes Staff. Ty Roush is a breaking news reporter based in New York City.Follow AuthorAug 20, 2026, 01:28pm EDTToplineModerna’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. In this photo illustration, a smartphone displays the logo of Moderna, Inc., an American biotechnology company specializing in messenger RNA (mRNA) medicines and vaccines, in front of a screen showing the company's latest stock market chart on July 23, 2026 in Shenzhen, China. (Photo illustration by Cheng Xin/Getty Images)Getty ImagesKey FactsShares of Moderna plunged more than 25% to around $129 as of early Thursday afternoon, a retreat from the firm’s record-setting 176% surge Wednesday that more than doubled the stock’s value, to above $174.Skyrocketing shares followed Moderna's announcement that its personalized cancer drug—an mRNA-based shot combined with Merck’s immunotherapy drug Keytruda—helped reduce the recurrence of melanoma and significantly extended the time patients lived without their melanoma returning.A decline appears to represent investors taking profits from the stock surge, and Wall Street still applauded Moderna’s trial results: Bank of America analyst Alec Stranahan, who more than quadrupled his share price target for Moderna to $170 from $40, called the results a “watershed moment” for the firm, allowing it to further diversify from infectious disease.Stranahan noted we “still don’t know how much better” Moderna’s combined drug is than Keytruda alone, and that more testing would likely be necessary. if (!window.cnxel) { window.cnxel = {}; window.cnxel.cmd = []; var iframe = document.createElement('iframe'); iframe.style.display = 'none'...