NEW YORK (Standard & Poor's) April 25, 2002--Standard & Poor's said today it assigned its triple-'B'-minus senior debt rating to property/casualty specialty writer Markel Corp.'s proposed $75 million 7.2% notes due 2007 and $100 million 7% notes due 2008. Standard & Poor's also said that it affirmed its other ratings on Markel Corp. and its subsidiaries. The outlook is negative. "The ratings on the proposed Markel notes reflect the belief that Markel Corp.'s financial flexibility remains good, despite recent operating losses," said Standard & Poor's analyst Laline Carvalho. Markel Corp.'s financial leverage is not expected to increase with the issue of the proposed notes, since they are part of the holding company's offering to exchange two series of notes from