The invention relates to a process for the preparation of a multimodal A-olefin polymer comprising polymerizing in a polymerization stage at least one A-olefin in the presence of a multisite catalyst and an adjuvant so as to produce a polymer having a relatively lower molecular weight component and a relatively higher molecular weight component, said adjuvant being selected from the group consisting of phosphines, phosphites, acetylenes, dienes, thiophenes and aluminium alkyls and said adjuvant being capable of altering the ratio of the fraction of higher molecular weight component to the fraction of the lower molecular weight component by at least 10%.