Squeezed by stricter regulations, a sputtering economy and anemic markets, financial institutions are finding profits hard to come by on both Main Street and Wall Street. A steep drop in mortgage lending and a slowdown in securities trading fueled a 7.6% drop in net income in the first quarter from the same period a year ago at the nation’s 6,730 commercial banks and savings institutions, according to data released by the Federal Deposit Insurance Corp. It was just the second time in 19 quarters that financial firms reported a year-over-year profit fall, the FDIC said.