** Shares of biotech firm IGM Biosciences IGMS.O slump ~69% to $1.92 premarket

** On Thursday, IGMS said it is halting further development of 2 drugs, imvotamab and IGM-2644, that 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

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

** As of Dec. 31, 2023, co had 224 full-time employees - SEC filing

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

** RBC downgrades stock to "sector perform" from "outperform" and 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))