The present invention relates to a composition, which comprises (a) a compound of formula (A-1) (b) a compound of formulae (B-1), (B-11), (B-111) or (B-IV) wherein Z1 is linear C12-alkyl or linear C18-alkyl, and (c) a compound, which is a further sterically hindered phenolic antioxidant. The composition is used for stabilization of an organic polymer against degradation by heat, light and/or oxidation. The organic polymer is for example a styrene-butadiene copolymer, a styrene-isoprene copolymers or polybutadiene.