An additive mixture containing a dibenzoate and either or both of a compound containing at least one structural unit and a compound containing at least one structural unit is disclosed. The additive combination enhances the processability of a thermoplastic molding composition that contains a (co)polymer of styrene, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic anhydride and N-substituted maleimide and a graft copolymer.