The class action lawsuit targets the period between May 13, 2025, and February 19, 2026, a window during which the company repeatedly signaled confidence in its NHS-Galleri trial. According to the complaint, GRAIL management maintained that the study’s three-year duration was statistically sound, despite allegedly possessing internal data suggesting that timeframe was inadequate to meet its primary endpoint.

The facade crumbled on February 19, 2026, when the company admitted the trial failed to hit its goals, conceding that a longer follow-up period should have been implemented. This revelation wiped out $2.2 billion in market capitalization overnight. Hagens Berman, the firm leading the litigation, is now investigating when exactly management recognized the discrepancy between their public optimism and the reality of the trial's design flaws. Investors who suffered losses have until August 4, 2026, to act as lead plaintiffs.