A resin composition comprises 100 parts by weight of a thermoplastic resin and 9 to 55 parts by weight of an additive mixture comprising (A) 3 to 35 parts by weight of a tetrahalogenated bisphenol A carbonate oligomer, (B) 3 to 35 parts by weight of bis(tribromo-phenoxy) ethane and (C) 0.5 to 15 parts by weight of antimony trioxide. It is advantageous in respect to flame retardancy, impact resistance and light durability.