Amazon's Prime Day 2025 is off to a rocky start, at least by one account. Momentum Commerce, which manages online sales for 50 brands in a variety of product categories and price points, said its Amazon (AMZN) sales plunged 41% on the opening day,

The summer sales calendar now revolves around Amazon's anchor, with most major U.S. retailers scheduling competing events within days of Prime Day's expanded four-day window.

Independent businesses that sell goods through Amazon account for more than 60% of the company’s retail sales. Some third-party sellers are expected to sit out Prime Day and not offer discounts to preserve their profit margins during the ongoing tariff uncertainty, analysts said.

Warehouse workers and union representatives said Prime Day meant extra hours in sometimes sweltering temperatures and a heightened risk of injuries.