Holiday season e-commerce spending continues to boom, with sales up 12 percent for the first 40 days of the season, according to market research firm comScore.

Holiday sales to date are $21.95 billion, up 12 percent from a year ago. The most recent week ended Dec. 10 saw online sales hit $5.15 billion, up 11 percent from a year ago. Two of the days surpassed $900 million in sales.

The question is whether online sales are taking market share away from traditional physical retail sales or if everyone is seeing solid growth. If the economy is improving, then both online and physical retailers could both be benefiting. But the odds are likely that online retailers are stealing market share. The strong performance shows that online merchants are perfecting their promotions and are getting better at targeting consumers with the right offers.

The comScore stats begin tracking the holiday sales starting Nov. 1. Gian Fulgoni, chairman of comScore, said that the growth rate so far is consistent with earlier forecasts.

“It’s clear that while deal-seeking shoppers may have driven stronger than anticipated spending early in the season, Americans continue to demonstrate a significantly greater willingness to spend online this year than in seasons past,” he said. “This coming week, beginning with Green Monday, should see some of the heaviest online shopping activity of the season and we expect at least one more day to surpass the billion dollar spending threshold.”

eBay coined the term Green Monday in 2007 as the day when one of the heaviest shopping days of the year occurs. Online sales typically peak before physical sales because merchants have to allow time for shipping to get goods to consumers before Christmas Day. A year ago, Green Monday on Dec. 14 came in at $854 million in sales. This year is expected to be another strong day. Free shipping by online retailers (where the shipment is guaranteed to get there before Christmas) has been extended until Dec. 17. That could actually extend the online sales season.

Since comScore started tracking e-commerce spending in 2001, it has seen only five shopping days eclipse $900 million in single-day spending. To date, Cyber Monday (Nov. 29) has been the only billion-dollar shopping day on record.

[photo credit: the mo down]

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