Thermoplastic molding composition comprising (A) 40 to 80 wt.-% SAN copolymer (S/AN-ratio 78:22 to 65:35, Mw 80,000 to 250,000 g/mol); (B) 20 to 60 wt.-% SBC block copolymer (monovinylarene 61 to 64 wt.-%) comprising conjugated diene/monovinylarene tapered polymer blocks; and (C) 0 to 5 wt.-% additives and/or processing aids (C); exhibiting ultra-high melt flow with good mechanical, thermal and optical properties, a process for its preparation and its use for the production of bulky and/or thin walled articles.