(Adds CEO, analyst comments, byline)

By Muralikumar Anantharaman

BOSTON, Feb 21 (Reuters) - U.S. research firm Morningstar Inc (MORN.O: Quote, Profile, Research) posted a 47 percent rise in fourth-quarter profit on Thursday, helped by acquisitions and rising demand, but the earnings missed estimates due to a higher tax rate.

Morningstar said while it was largely unaffected by the credit crisis in 2007 as it dealt mainly with the relatively safe asset management units of financial firms, the rising cutbacks in staff and resources at these firms posed a risk this year.

"I suppose it's a risk as we enter the new year," Morningstar Chairman and Chief Executive Joe Mansueto told Reuters in an interview.

"If you look at our results for last year, we had a pretty healthy year despite cutbacks at some firms. It's something that we are monitoring. I think there's concern among clients," he said.

Morningstar, known for its star system of rating mutual fund performance, said fourth-quarter net income increased to $20.0 million, or 41 cents a share, from $13.6 million, or 29 cents a share, in the same quarter of last year.

Analysts had on average expected earnings of 43 cents a share, according to Reuters Estimates.

"It's all in the tax rate," said Murali Gopal, an analyst at Keefe, Bruyette & Woods. Morningstar said its effective tax rate was 42.4 percent, while Gopal said he had expected a tax rate of 40 percent. "Overall, it was a pretty strong quarter," he said.