USA: SHOP TILL YOUR TABLET RUNS OUT OF JUICE: Cyber Monday was largest online shopping day in US history - by Lauren Thomas

Digital transactions on Monday reached a record $6.59 billion, Adobe Insights unveiled Tuesday in its final update on the holiday weekend.

That marks a 16.8 percent increase from a year ago, and makes Monday the largest online shopping day in U.S. history.

Mobile also had a record day, Adobe found, saying smartphones have become the "de facto device" for on-the-go shopping. Mobile sales on Cyber Monday reached $2 billion for the first time.

"This year, mobile shopping was dominant both in the morning and afternoon, and desktop only staged a comeback in the evening when people were home," Taylor Schreiner, director of Adobe's Digital Insights division, said.

Adobe measures 80 percent of online transactions from 100 major U.S. retailers.

Read more: Cyber Monday was largest online shopping day in US history