Amazon recorded the biggest uplift, rising from 26.5% on September 1 to 33.7% on September 25 - a gain of 7.2 percentage points. The surge followed the company's UK Upfront event, which promoted new advertising formats across Prime Video and its growing retail media network. The e-commerce giant also announced a landmark partnership with Netflix on September 10, allowing advertisers to buy inventory from Netflix's ad-supported tier directly through Amazon's demand-side platform (DSP).