Aspen Insurance agreed to a $3.5 billion cash takeover by Japan's Sompo at $37.50/share, a 35.6% premium. Citi and JMP cut ratings, saying rival bids are unlikely, while Wells Fargo lifted its target to match the offer. The deal adds $4.6 billion in premiums, Aspen's Lloyd's syndicate, and strong specialty lines to Sompo's global portfolio.