The regional Stoxx 600 index was down 0.37% at 11:20 a.m. in London, with autos stocks leading losses. France's CAC 40 index dropped 0.8% as investors assessed credit rating agency Moody's surprise Saturday decision to downgrade the country's score to Aa3, from Aa2 previously. The agency said French public finances would be weakened in the coming years by ongoing political instability.