comScore, Inc., a leader in measuring the digital world, released its Q4 2009 U.S. retail e-commerce sales estimates, which showed that online retail spending reached $39 billion, up 3 percent versus year ago. Total retail e-commerce spending reached $129.8 billion for the full year 2009, marginally below the previous year’s total of $130.1 billion.

“The fourth quarter, with 3 percent year-over-year growth, helped end what has been a disappointing year for online consumer spending on a more positive note,” said comScore chairman Gian Fulgoni. “As we head into 2010, there is reason for guarded optimism for online retail spending to continue to gain share of consumers’ wallets. At the same time, I expect absolute growth to be stymied by continued high unemployment and the deleveraging that is occurring in the economy as consumers exercise their new-found propensity to save.”

Other highlights from Q4 e-commerce include:

- Spending growth was driven by an increase in online buyers, while average spending per buyer saw modest declines.

- Tuesday, December 15 ranked as the heaviest U.S. online spending day in history at $913 million.

- The largest online retailers, led by Amazon and Walmart, gained market share of e-commerce sales versus small and medium-sized retailers.

- Free shipping factored into more than 40 percent of e-commerce transactions during the holiday season.