Arcus Biosciences Inc. (RCUS) experienced a significant after-hours plunge of 5.49% following the release of its first-quarter 2026 financial results, which fell short of analyst expectations on key metrics.

The biopharmaceutical company reported a quarterly loss of $1.02 per share, missing the consensus estimate of $0.93 per share. More notably, revenue of $17 million represented a substantial miss against the expected $29.484 million and marked a 39.29% decline compared to the same period last year. The company's net loss widened to $128 million from $112 million a year earlier.

The revenue decline was primarily attributed to lower development services revenue from the company's collaboration with Gilead Sciences. Despite ending the quarter with $876 million in cash and projecting a runway into at least the second half of 2028, the significant earnings and revenue misses prompted a negative market reaction in post-market trading.