Why Grail Shares Are Plummeting

A large clinical trial of the company's cancer screening test did not produce the desired result.Shares of cancer-detection firm Grail (GRAL 14.38%) fell by half in last Friday's trading session. That's quite a turnabout after the company's share price more than quintupled in 2025, from about $19 a share in January to $110 in November. Last week shares of the California-based biotech were trading at around $102. Today they're priced at $49. What happened? Image source: Getty Images. Well, Grail makes a multi-cancer early detection test called Galleri that screens for a signal in the blood shared by more than 50 types of cancer. Cancers growing in the human body shed their DNA into the bloodstream, and the Galleri test can detect that DNA very early on -- hopefully, early enough for effective treatment. If that sounds like an incredible innovation in the world of cancer detection, that's because it is. But investors need to know that the test works and can reduce late-stage cancer diagnoses. On Thursday the company announced that, in a large clinical trial in England, the Stage III-IV cancer reduction goals were not met. According to a Grail press release, "The primary endpoint of statistically significant Stage III-IV reduction was not observed." ExpandNASDAQ: GRALGrailToday's Change(-14.38%) $-7.22Current Price$42.99Key Data PointsMarket Cap$2.0BDay's Range$41.50 - $48.4552wk Range$20.44 - $118.84Volume188KAvg Vol1.1MGross Margin-5053.88% Grail has been working hard to get the U.S. government to cover its Galleri test under Medicare -- the holy grail for any healthcare treatment or test. It's not clear now if that goal is less achievable. But it is clear that Galleri will have to perform better in other trials. Until that happens, the company's share price will linger at a much lower level than it recently enjoyed.Read NextFeb 23, 2026 •By Lee SamahaHere's Why Grail Stock Slumped Again TodayFeb 20, 2026 •By Lee SamahaHere's Why Grail Stock Crashed 50% TodayJan 22, 2026 •By Lee SamahaHere's Why This Exciting Healthcare Stock Popped 13% TodayDec 2, 2025 •By Lee SamahaHere's Why Grail Soared, Again, in NovemberNov 17, 2025 •By Eric VolkmanWhy Grail Stock Zoomed Nearly 7% Higher on MondayNov 6, 2025 •By Lee SamahaHere's Why Grail Stock Exploded Higher by 55% in OctoberAbout the AuthorMatthew Benjamin is a contributing Motley Fool stock market and investing analyst covering publicly-traded companies across all sectors. Prior to The Motley Fool, Matt was a senior markets expert at an investing newsletter in Baltimore, an editorial consultant to the World Bank and the International Monetary Fund (IMF), and an economics correspondent at Bloomberg News. He holds a B.A. from Bucknell University and an M.A. from New York University. Fun fact: Matt has met every Federal Reserve Chair from Paul Volcker through Jerome Powell.TMFMbenjamin68Stocks MentionedGrailNASDAQ: GRAL$42.99 (14.38%) $7.22*Average returns of all recommendations since inception. Cost basis and return based on previous market day close.