Moody's says subprime loss estimates a "crapshoot"

NEW YORK (Reuters) - The review by Moody's Investors Service of the top ratings of bond insurers is taking time because "we're taking a great deal of care to get the answer right," Moody's Chief Credit Officer Andrew Kimball said on Thursday.

Kimball added that there is "hysteria" in the markets over the expected cumulative losses from subprime residential mortgages, but at the end of the day no-one really knows how large they will be, saying "it's a crapshoot."

"At the end of the day we'll make that call with due care," he told a conference organized by the New York Society of Security Analysts.

The potential for a rating downgrade to drive an insurer out of business, and the potential knock-on effects from any possible downgrade require that care is made in reviewing the companies, Kimball added.

Bond insurers are under review because ratings agencies argue that they do not have enough capital to hold the top "Aaa" ratings due to exposures to risky residential mortgages in their insurance portfolios.

(Reporting by Karen Brettell; Editing by James Dalgleish)