Robust demand from subprime customers spurred growth in U.S. unsecured loans last year with their combined balances surging 10% to a new high of $276 billion, according to TransUnion's Credit Industry Insights Report. Some 26.4 million consumers carried those loans as of end-December, up from 24.5 million a year earlier. "As interest rates began to fall, many consumers are consolidating their credit card balances into unsecured loans," said Michele Raneri, vice president and head of U.S. research and consulting at TransUnion.