GRAIL, Inc. (NASDAQ: GRAL) experienced a sharp decline of 30.09% in after-hours trading following the release of its fourth-quarter financial results and pivotal trial data.

The stock's steep drop came after the company reported that the primary endpoint of statistically significant combined Stage III-IV cancer reduction in its landmark NHS-Galleri trial was not met. While the trial demonstrated positive secondary outcomes, including a substantial reduction in Stage IV cancer diagnoses and increased early-stage detection, the failure to achieve the main statistical goal represents a significant setback for the multi-cancer early detection test.

Concurrently, GRAIL reported quarterly earnings that beat analyst estimates but sales that slightly missed expectations. The company also announced plans to extend the trial's follow-up period by 6-12 months, which may delay regulatory pathways and commercial timelines.