The invention relates to thermoplastic ABS molding compositions comprising components A) and B): A) from 5 to 80% by weight of a graft polymer A) having bimodal particle size distribution; and B) from 20 to 95% by weight of a thermoplastic polymer B) having a viscosity number VN of from 50 to 120 ml/g. The invention further relates to a process for the preparation of graft copolymer A and to the graft copolymer made by that process.