A thermoplastic molding composition having improved properties is disclosed. The composition comprises polycarbonate resin, a first graft polymer, a first free copolymer, a second graft polymer and a second free copolymer; the weight-average molecular weight of the first free copolymer being lower by at least 32,000 g/mol with regard to that of the second free copolymer. The inventive composition features improved balance of melt flowability and ductility, good resistance to hydrolysis and process stability.