Online sales during the US retail sector's Cyber Monday promotion grew 16 percent from last year to $2.29 billion, lifted by more shopping on mobile devices, a market tracker said Tuesday.
The Adobe Digital Index survey said online sales for the key holiday shopping day reflected an 80 percent jump in sales from mobile devices like smartphones and tablets.
Mobile accounted for some 18.3 percent of online sales.
Cyber Monday stems from the early days of the Internet, when consumers would use their fast Internet connections at work to make online holiday purchases.
But many US retailers are extending their deals over several days from the Thanksgiving Day holiday on Thursday.
"Retailers earned 10 percent of their holiday sales in just the last five days, an increase of 26 percent year-over-year," said Tamara Gaffney, principal analyst for Adobe Digital Index.
Adobe's online shopping data is based on an analysis of nearly 900 million visits to 2,000 retailer websites on Cyber Monday and more than three billion visits since Thanksgiving Day.
A separate analysis by IBM showed Cyber Monday was the biggest online shopping day in history with a 20.6 percent increase in online sales. IBM said 17 percent of total online sales came from mobile, an increase of 55.4 percent year-over-year.
"We continue to see a dramatic movement of the new digitally savvy consumer as Cyber Monday once again proved to be the star of this holiday shopping season," said Jay Henderson of IBM.
"The mobile device has become the shopping companion of choice for consumers, driving record mobile sales."
Wal-Mart Stores said Monday saw "the biggest online sales day" in its history, without providing a specific dollar amount.
A Wal-Mart statement said the website saw more than one billion page views in the five days from Thanksgiving, and strong sales of large-screen televisions, iPads and Mega-Bloks toys, among other items.
"We had an all-time record sales day yesterday as the momentum we saw on Thanksgiving carried through to Cyber Monday," said Wal-Mart's Joel Anderson.
The retail technology group Mercent said sales on its supported channels grew 33 percent from a year ago. It said Google shopping saw 54 percent growth and Amazon 23 percent.
Forecasters project just three to four percent growth in the entire retail sector this holiday season, while online shopping is expected to soar 13 to 14 percent in the 2013 season.
Explore further: 'Cyber Monday' sizzles with US online shopping