JPMorgan is struggling to earn its keep. The lender run by Jamie Dimon cranked out a better-than-expected $6.2 billion in second-quarter profit, it said on Thursday. That came courtesy of jumps in lending and trading revenue as well as falling costs. The trouble is, even with these top-line improvements the company's annualized return on equity was just 10 percent in the quarter. That barely covers the firm's cost of capital.