(Updates)

** Shares of biotech firm IGM Biosciences slump 68.5% to $1.95, hitting their lowest level since Nasdaq debut in September 2019

** Stock on track for biggest one-day percentage fall since debut, if losses hold

** IGMS said on Thursday it is halting further development of two drugs, imvotamab and IGM-2644, which were being tested for immunity-related diseases

** Early-stage trail data shows imvotamab is not effective enough in depleting B cells, a type of white blood cells, for rheumatoid arthritis and systemic lupus erythematosus, CEO Mary Beth Harler says

** Co also plans to lay off about 73% of its employees

** Co had 224 full-time employees as of Dec. 31, 2023 - SEC filing

** RBC Capital Markets notes IGMS's preclinical collaboration with Sanofi for undisclosed I&I (immunology and inflammation) targets but does not expect it "to drive near-term value"

** Brokerage downgrades stock to "sector perform" from "outperform", cuts PT to $1.50 from $20

** At least three other brokerages also downgrade stock and cut PT

** IGMS declined ~30% in 2024

(Reporting by Kamal Choudhury in Bengaluru)

((Kamal.Choudhury@thomsonreuters.com))