WASHINGTON, May 26 (Reuters) - U.S. bank profits rose 29.1% during the first quarter of 2021 from the previous quarter as banks adjusted expectations for future credit losses downwards, a bank regulator said on Wednesday. The industry posted $76.8 billion in first-quarter profits, up from $58.3 billion a year prior and $17.3 billion in Q4 2020, the U.S. Federal Deposit Insurance Corporation (FDIC) said. It added that three-fourths of all banks (74.8 percent) reported higher quarterly net income compared with the year-ago quarter and that the share of unprofitable institutions dropped from 7.4 percent a year ago to 3.9 percent. Loan balances declined from the previous quarter and year driven by a reduction in credit card balances, the agency added. (Reporting by Katanga Johnson)