The whiteness and stability of a polyolefin have been found to be improved upon addition of a first phosphite, an arylalkyl diphosphite, and a second phosphite selected from a second arylalkyl disphosphite or a triarylphosphite. In addition, the addition of a triarylphosphite with an arylalkyl disphoshite has been found to improve the hygroscopic nature and the hydrolytic stability of the arylalkyl disphosphite.