UPDATE: Stifel Nicolaus Downgrades Markel Corporation to Hold Following Acquisition

Stifel Nicolaus reduced its rating on Markel Corporation (NYSE: MKL ) from Buy to Hold and removed its $550 price target. Stifel Nicolaus commented, "We are downgrading the shares of Markel to Hold from Buy following its announced acquisition of Alterra (ALTE: $28.18, Not Covered). We think Markel's own