Additionally, the rating firm is wary about the possibility that there might not be renewal of the federal Terrorism Risk Insurance Act, which provides a government backstop in the event of attacks inflicting super-catastrophe losses.

In reviewing insurer capital strength, Mr. Upton said that changes in frequency estimates by catastrophe modelers have led them to put an increased charge into their assessment.

Discussing another aspect of the market, he said the interest of newer, short-term investors in such offerings as catastrophe bonds and reinsurance sidecars is being generated not only by good returns in the current environment, but because they offer investments that are negatively correlated with their other risks.

However, he believes that "if property-cat rates drop, at some point they would drop out."

Mr. Upton said the presence of such investors has been healthy for the marketplace, adding that even if they were to drop out due to falling prices, if catastrophe rates rebound, these same investors would return.

"These unusual instruments are a very positive thing," Mr. Upton commented, adding that they would only be viewed as a concern if a reinsurer became excessively dependent on them. However, he was quick to note that he was unaware of any reinsurer that was in such a situation.