Artiva Biotherapeutics, Inc. shares fell $1.89 per share, or 30.68%, to close at $4.27 on October 27, 2026, after the Company announced that it was discontinuing further development of AlloNK (AB-101), its lead allogeneic natural killer cell therapy candidate being evaluated for rheumatoid arthritis and other B-cell-driven autoimmune diseases. The Company stated that the decision followed a review of updated longer-term clinical data indicating that the durability of clinical responses did not meet expectations. Artiva also disclosed recent Grade 5 (fatal) safety events involving the deaths of two patients in its clinical studies. In connection with halting the lead program, the Company said it would implement a workforce reduction of approximately 94% and would explore strategic alternatives that could include a merger, an asset sale, or a complete dissolution and liquidation of the business. The announcement combined the loss of the Company's lead development program, the disclosure of fatal patient outcomes in its trials, and a near-total reduction of its workforce in a single day, and shareholders absorbed the resulting decline in the share price. The investigation concerns whether Artiva Biotherapeutics, Inc. adequately disclosed the durability of clinical responses for AlloNK (AB-101) and the safety events in its clinical studies ahead of the October 27, 2026 announcement discontinuing the program.