Amazon.com Inc.’s Prime Day opened to a weaker start than last year, with sales on the first day of the promotion falling 41% year over year, according to data from brand-advisor Momentum Commerce, which tracks online performance for about 50 consumer products companies. The decline deepened from the event’s first four hours, when Momentum Commerce measured a 14% drop from the comparable period in 2024. Amazon expanded the sale to four days this year from the customary two, a change the research firm says is prompting shoppers to browse and delay purchases in hopes of better deals. Chief Executive Officer John Shea said overall revenue could still finish 9.1% higher than last year’s two-day event if customers complete transactions later in the week. Amazon Vice President for Prime Jamil Ghani said in a Bloomberg Television interview that customers are gravitating toward everyday essentials and that the company is “pleased by the engagement” early in the event. Amazon shares were up about 1.5% at $222.65 in afternoon New York trading.