NEW YORK (Standard & Poor's CreditWire) Aug. 16, 1999--Standard & Poor's today placed its ratings on Markel Corp. Group (see list) and related entities on CreditWatch with negative implications. The action follows Markel's announcement of its planned acquisition of Terra Nova (Bermuda) Holdings Ltd. for about $905 million. Markel will also assume $175 million of Terra Nova debt. The completion of this transaction is subject to regulatory and shareholder approval. On Aug. 12, 1999, Standard & Poor's placed its ratings on Terra Nova and its related entities on CreditWatch with developing implications (see list) following the company's announcement that it was reviewing its strategic alternatives. Standard & Poor's believes integration risk is significant given the size of Terra Nova, which