LONDON (Standard & Poor's CreditWire) March 31, 2000--Following the close of Markel Corp.'s acquisition of Terra Nova group companies, Standard & Poor's today lowered its ratings on U.S.-based insurer Markel and related entities, and removed them from CreditWatch, where they were placed on Jan. 26, 2000 with negative implications. At the same time, Standard & Poor's took various rating actions on Bermuda-based insurer Terra Nova. See list below for all ratings actions. Standard & Poor's today also withdrew its counterparty credit and financial strength ratings on Investors Insurance Co. of America (Investors) as a result of its sale to Lumbermens Mutual Casualty Co. (A/Stable/--). All existing liabilities were reinsured to an operating affiliate before the sale, with renewal rights being