A last-minute push in orders made through Amazon's Prime Now service helped the online retailer recover the ground it lost to bricks-and-mortar competitors earlier in the season and maintain its dominant market share from the 2015 season.
According to new data from Slice Intelligence, which scanned more than 1 million digital shopping receipts, Amazon accounted for 38 percent of online sales from Nov. 1 to Dec. 29. That's in line with the same period in 2015, when 37.9 percent of online revenue went to Amazon, according to Slice.
Heading into the final stretch of the holidays, Amazon had ceded some share to competitors. But its portion of spending increased as the clock wound down, and consumers became more dependent on quick deliveries.
Amazon's lift was largely the result of Prime Now, which offers one- and two-hour delivery in dozens of markets. The service is available for two dozen categories, including household items and electronics.
Known for its tight delivery windows, Amazon has demonstrated to Prime members that it can get them last-minute orders on time. In a news release last month, the company said that Dec. 23 was the biggest day ever for Prime Now, and that members ordered three times more items through the service compared with last year.
"2017 is clearly becoming the year [once again] that Amazon's competitors have no choice but to think differently in order to counter Amazon's dominance in the e-commerce channel," Ken Cassar, principal analyst at Slice, told CNBC in an email.
He added that Wal-Mart's more than $3 billion investment in Jet.com "will soon be seen as a bargain."
Also in December, Amazon said it had recruited more shoppers to its subscription Prime program than during any other holiday season, helping it reach a sales record. It shipped more than 1 billion items worldwide with Prime and Fulfillment by Amazon.
Part of that lift may be the result of a more aggressive marketing campaign. An analysis released by MediaRadar last month found that Amazon dramatically increased its spending on TV and digital ads this season.
Adobe Digital Insights on Wednesday said online sales increased 11 percent this holiday season, to $91.7 billion. That was in line with its initial forecast. Adobe's data measures 80 percent of all online transactions from the top 100 U.S. retailers.