** Shares of insurer James River Group slide as much as 19.6%, last down 16.9% at $5.50

** JRVR late Monday reported Q3 net loss of 74 cents/shr, compared with Wall Street expectations of a profit of 15 cents/shr - LSEG data

** Q3 results included $57 mln of unfavorable reserve development in JRVR's excess and surplus lines segment

** Reserves are funds set aside by insurers to meet any future claims it may have to payout

** Q3 combined ratio was 135.5%, higher than Street expectations of 121.8%

** Combined ratio measures the underwriting profitability of an insurer

** A ratio above 100% indicates the insurer is paying out more money than it is receiving in premiums

** As of last close, JRVR shares were down 28.4 YTD

(Reporting by Arasu Kannagi Basil in Bengaluru)

((ArasuKannagi.Basil@thomsonreuters.com;))