XL Capital's share dropped below the $20 mark by $1.07 or 5.11 percent to $19.87, having sunk to its lowest level for 13 years earlier in the week.

Meanwhile XL Capital Group's ratings have been placed in CreditWatch with negative implications, by Standard & Poor's Ratings Services (S&P).

"The action was taken because of our concern that earnings, capitalisation, and financial flexibility might be adversely affected by the uncertainty surrounding XL's outstanding reinsurance agreements and guarantee of business underwritten by the operating subsidiaries of bond insurer Security Capital Assurance, or SCA, prior to the SCA IPO (initial public offering) by XL in August 2006," said Steven Ader, a credit analyst at S&P.

The ratings agency believes that without a replenishment of capital, a charge exceeding $500 million could result in the rating being lowered.

XL Capital Ltd. has a long-term rating of A- with a stable outlook.