Oct. 10 (Bloomberg) -- MetLife Inc., the biggest U.S. life insurer, said a ``major'' credit-rating firm will conduct a review in the fourth quarter that may have ``a material adverse effect'' on results and the company's financial condition.

``The difficulties experienced recently by many financial institutions, including our competitors in the insurance industry,'' may prompt ratings companies to ``heighten the level of scrutiny'' for their reviews, New York-based MetLife said today in a regulatory filing.

Life insurance stocks have been pummeled in the last two weeks and Fitch Ratings lowered the industry's outlook on concern that investment losses could erode capital. MetLife, which has dropped 46 percent this month, sold $2 billion in stock on Oct. 8 after reporting a third-quarter profit slide and a $7 billion increase in unrealized losses.

Rating firms, including Standard & Poor's, Moody's Investors Service, A.M. Best Co. and Fitch may increase the capital required to maintain credit grades, MetLife said. It didn't identify which firm will do the review.

MetLife spokesmen Christopher Breslin and John Calagna didn't immediately return telephone calls and e-mail messages seeking comment. The company disclosed the review in the share sale prospectus.

To contact the reporter on this story: Andrew Frye in New York at afrye@bloomberg.net.

Last Updated: October 10, 2008 20:05 EDT