According to a Reuters report, borrowing by U.S. small businesses rose in December to the highest level in more than four years, pointing to continued strength in an important corner of the economy.

Per the report, the Thomson Reuters/PayNet Small Business Lending Index, which measures the overall volume of financing to U.S. small businesses, jumped 19% in December, its 17th consecutive double-digit rise, PayNet said on Wednesday.

At 112.6, the index matched the level registered in November 2007; it was last higher in August of that year, as the subprime mortgage bubble was bursting.

"The data show there's some underlying strength," PayNet founder Bill Phelan said in an interview. "When you get these capital project investments, you can really move the needle on the economy."

As reported, the U.S. economy grew at its fastest pace in 1-1/2 years last quarter, despite a beleaguered housing market and lackluster consumer spending. The PayNet survey suggests growth could continue, at least for the next few months. PayNet tracks borrowing by millions of small U.S. businesses, and the index is correlated with changes in U.S. gross domestic product a quarter or two in the future.
Small businesses historically account for a disproportionate share of jobs growth.

The report cites that separate PayNet data suggested one worrisome sign in the financial picture at small businesses: some are having a bit more trouble paying back their debt. Accounts in moderate delinquency, or those behind by 30 days or more, rose to 1.56% in December, from 1.53% in November, the first increase in nearly two years.

"I don't think this is Paul Revere making the call about impending invasion, but it certainly is something to keep an eye on," Phelan said.

Accounts 90 days or more behind in payments, or in severe delinquency, fell to 0.38% in December, a record low, from 0.40% in November. Accounts behind 180 days or more, or in default and unlikely ever to be paid, fell to 0.53% in December, from 0.58 percent in November, according to PayNet.