Wall Street is bracing for regional and small banks to fess up to large losses from their mounting volume of soured construction loans made primarily to home builders.

According to the Federal Deposit Insurance Corp., $45.4 billion of the $631.8 billion in construction loans outstanding at the end of the first quarter were delinquent. When banks announce second-quarter results in coming weeks, they are expected to report sharp increases in loans that builders can't repay. Banks are also facing intensifying pressure from federal...