Molding compositions having improved properties for low-pressure, low-shear molding techniques are prepared by carrying out a two-stage polymerization of an initial mixture comprising a polymerizable monomer selected from the group consisting of (1) a polymerizable aromatic monoalkenyl monomer or (2) a mixture of such aromatic monoalkenyl monomer with another polymerizable monovinyl monomer; in the presence of a butadiene rubber elastomer under bulk polymerization conditions, followed by suspension polymerization conditions; the process being characterized by the incorporation into the initial mixture of 1 to 10 wt. %, based on the polymerizable monomers, of a straight chain saturated polyester having an average molecular weight of 1,000 to 50,000.