Earnings dropped at Moody's Corp. (MC), the parent company of credit ratings agency Moody's Investors Service, as U.S. revenue shrank and expenses grew during the fourth quarter.

The company earned $96.2 million during the quarter, or 43 cents per share, down 30% from the same period the year before. Revenue at Moody's both foreign and stateside was $567.1 million, up slightly from $564.3 million a year earlier.

But revenue in the U.S. for the credit rating agency operation dropped 9% to $205.3 million in the fourth quarter.

The $395 million in expenses at Moody's increased 7% from the year before. Margins shrank, the company said, as it took on more employees and made new technology investments.

Revenue for the entire year was $2.2 billion, up from just over $2 billion in 2010. Moody's Investors Service totaled $1.5 billion in 2011, up 12% from the year before.

The company expects 2012 revenue to grow "in the high-single to low-double-digit percent range," according to its financial statement.

"Moody's achieved strong performance for full-year 2011, with growth in all lines of business at both Moody's Investors Service and Moody's Analytics despite volatile business conditions," said Raymond McDaniel, CEO of Moody's. "For 2012, we anticipate revenue growth across most areas of our business."