Provided are thermoplastic polymer composition comprising (a) a polyvinyl halide, and (b) an acrylic copolymer comprising 70 to 100 weight % of a first polymeric stage, based on the total weight of the acrylic copolymer, comprising polymerized units derived from at least 85 weight % of one or more C1-C6 alkyl methacrylate monomers and C1-C3 alkyl acrylate monomers, based on the total weight of monomers in the first polymeric stage, wherein the first polymeric stage has a calculated Tg of 70° C. or less, and wherein the acrylic copolymer has a molecular weight of greater than 1.5×106 g/mol.