NEW YORK--(BUSINESS WIRE)--Earnings at large US banks were generally up on a linked-quarter basis during second-quarter 2015 as the industry showed some glimmers of improving net interest margins, says Fitch Ratings. Among the 12 large banks with material loan portfolios included in Fitch's quarterly US bank earnings report, half reported margin expansion. It is unclear whether this marks an inflection point for these banks, but it does reverse a multi-quarter trend of NIM compression due to th