** Shares of biotech firm Alvotech ALVO.O fall 28.8% to $5.45

** Late on Sunday, company said the U.S. FDA issued complete response letter declining approval for Alvotech's drug, AVT05, a biosimilar to Johnson & Johnson's JNJ.N Simponi for treatment of patients with rheumatoid arthritis

** FDA cites unresolved deficiencies from July 2025 inspection of Alvotech's Reykjavik, Iceland facility

** Company notes the facility remains FDA approved to manufacture and continues supplying currently commercialized products

** The FDA did not identify any other deficiencies with the application - ALVO

** Following the receipt of the CRL, Alvotech lowers its 2025 total revenues to a range of $570 million to $600 million, compared to a prior $600 million to $700 million

** Including session's moves, stock down 58.6% YTD

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))