A bisphosphite of the formula I wherein R1, R2, R3 and R4 are each hydrogen, an aliphatic, alicyclic, aliphatic-alicyclic, aromatic, aromatic—aromatic, aliphatic-aromatic hydrocarbon or heterocyclic or aliphatic-heterocyclic group having from 1 to 50 carbon atoms, F, Cl, Br, I, —CF3, —OR7, —COR7, —CO2R7, —CO2M, —SR7, —SO2R7, —SOR7, —SO3R7, —SO3M, —CO2NR7R8, NR7R8, N═CR7R8, NH2, where R1 to R4 are identical or different and may be covalently linked to one another; R7 and R8 are each hydrogen, a substituted or unsubstituted, aliphatic or aromatic hydrocarbon radical having from 1 to 25 carbon atoms, and may be identical or different; M is an alkali metal, alkaline earth metal, ammonium or phosphonium ion; Q is a substituted or unsubstituted divalent aliphatic, alicyclic, aliphatic-alicyclic, aromatic, aliphatic-aromatic hydrocarbon, heterocyclic or aliphatic-heterocyclic radical having from 1 to 50 carbon atoms where HO-Q-OH is a diol; W and X are each a substituted or unsubstituted aliphatic, alicyclic, aliphatic-alicyclic, aromatic, aromatic—aromatic, aliphatic-aromatic hydrocarbon, heterocyclic or aliphatic-heterocyclic radical having from 1 to 50 carbon atoms which may be identical or different or covalently linked to one another, provided that when the phosphite oxygens linked to W and X are each linked to an aromatic ring, then they are linked to different aromatic rings, metal complexes thereof, and a method for the hydroformylation of olefins.