The online spending in the US during 37 days of holidays has increased 13% to $26.6bn between November to December 7 compared to the corresponding period in 2011, according to a report from Comscore.

The most recent week saw three individual days where more than $1bn was spent online on consecutively increasing the number of days with spending of more than $1bn to seven.

Comscore chairman Gian Fulgoni said that the upcoming week led by Green Monday is expected to be the heaviest online spending week in history by delivering five billion-dollar days.

"Green Monday came to refer to that Monday near mid-December when online spending actually tended to peak as consumers hurried to finish their online shopping in time for shipments to arrive before Christmas."

"While we still see that steady build in spending continuing into mid-December, Cyber Monday’s intense promotional activity has vaulted it into the top spot in recent years while Green Monday has had to settle for a spot in the top three," Fulgoni added.