Disclosed is a method of preparing an ultra-high molecular weight, linear low density polyethylene with a catalyst system that comprises a bridged indenoindolyl transition metal complex, a non-bridged indenoindolyl transition metal complex, an alumoxane activator and a boron-containing activator. The ultra-high molecular weight, linear low density polyethylene has a weight average molecular weight greater than 1,000,000 and a density less than 0.940 g/cm.sup.3.