 OLDWICK, N.J.--BUSINESS WIRE-- insurance--AM Best has revised the outlooks to stable from negative and affirmed the Financial Strength Rating FSR of A- Excellent and the Long-Term Issuer Credit Ratings Long-Term ICR of a- Excellent of the rated operating subsidiaries of James River Group Holdings, Ltd. JRG Holdings NASDAQ: JRVR. In addition, AM Best has revised the outlook to stable from negative and affirmed the Long-Term ICR of bbb- Good of JRG Holdings. JRG Holdings is domiciled in P 