J.P. Morgan Chase & Company, the biggest U.S. bank by assets, posted sharply higher first-quarter profit as it spent less money on litigation, but most of its major businesses reported weak performances, and the bank's overall revenue declined. The bank said profit rose 34 percent to $6.1 billion in the January-March quarter from $4.6 billion in the same period a year ago. The profit figures easily surpassed Wall Street estimates. Revenue fell 3 percent to $25.8 billion, after excluding the effect of an accounting charge. The figure narrowly beat analyst expectations. The financial results reflected the pressure the bank is under even as it recovers from the disastrous “London Whale" trading losses that cost more than $6 billion last year. J.P. Morgan shares fell in premarket trading Friday. First-quarter profit in its consumer-banking segment fell 12 percent to $2.6 billion, and its corporate and investment-banking profit fell 2 percent to $2.5 billion. Profit rose in commercial banking and asset management, but the growth was too small to have much influence on overall results. J.P. Morgan funded $53 billion in mortgages, a jump of 37 percent from a year earlier, but profits in the mortgage unit fell 31 percent. Despite the higher quarterly profit, it has been a difficult year for J.P. Morgan. The surprising London Whale trading loss, which the bank acknowledged about a year ago, has been haunting it, resulting in management shake-ups, increased scrutiny from regulators, scolding from the U.S. Congress, and a big pay cut for chief executive Jamie Dimon. In a statement, Dimon said the bank has “work to do" to strengthen internal controls and make sure it is in compliance with regulations. He called it the new “top priority" for the company. “There is no room for compromise in meeting our obligations to comply with the new regulatory requirements and ensure that our systems, practices, controls, technology, and ... culture meet the highest standards," he wrote.