This once-hot cancer-detection company’s stock got cut in half after a failed trial

MarketWatch

by Tomi Kilgore

February 20, 2026

AI-Generated Deep Dive Summary

Grail’s stock plummeted on Friday after a pivotal trial of its Galleri cancer-screening test failed to meet its primary endpoint. The company’s shares, which had surged nearly 100% over the past year due to high investor expectations, lost more than half their value, making Grail the biggest loser on the Nasdaq. This sharp decline reflects the broader disappointment among investors who had hoped for groundbreaking results from the trial, which was seen as a critical step toward validating the test’s potential in early cancer detection. The Galleri test, designed to detect multiple types of cancers at an early stage, is central to Grail’s business strategy. The failed trial, however, casts doubt on its effectiveness and raises questions about the company’s future prospects. Grail’s struggles also have implications for Illumina, a major shareholder in the biotech firm and a key player in gene sequencing technology. The drop in Grail’s stock underscores the high risks and volatility inherent in the biotechnology sector, particularly in early-stage companies reliant on clinical trial outcomes. This development matters significantly to finance readers as it highlights the delicate balance between innovation and market expectations in the biotech industry. Investors often place heavy bets on promising startups like Grail, driven by the potential for groundbreaking medical advancements. However, such trials are inherently risky, and a failure can have cascading effects not only on the company’s stock but also on its partners and stakeholders. The situation underscores the importance of careful risk management and the need for companies to manage investor expectations, especially in high-stakes sectors like cancer detection and treatment.

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Originally published on MarketWatch on 2/20/2026