Let L1(x) and L2(x) be linearized polynomials over Fqn. We determine conditions when the product L1(x) . L2(x) is a planar mapping on Fqn. For a linearized polynomial L over Fqn, let M(L) ={α∈Fqn : L(x) + α x is bijective on Fqn}. We show that the planarity of the product L1(x) . L2(x) is linked with the set M(L) of a suitable linearized polynomial L. We use this relation to describe some families of such planar mappings and we give some nonexistence results.