Amazon Prime Day Sales Off 41% First Day, Brand Adviser Says

A worker sorts packages on Amazon Prime Day in New York on July 8.

Photographer: Klaus Galiano/Bloomberg

Amazon.com Inc took a big gamble this year by expanding its annual Prime Day summer sale to four days from two, betting the extension would give shoppers more time to navigate the millions of deals on its sprawling web store.

Some of the preliminary results are grim, raising the stakes for the event’s remaining days.