US online retail spending rose by 9% to $32.9bn in the second quarter of 2010, compared to $30.17bn in the same period a year ago, representing third consecutive quarter of positive year-over-year growth following a year of flat or negative growth rates, according to data released by comScore.

The report said that upper-income households (those earning at least $100,000 annually) grew 17 % versus year ago, approximately twice the overall e-commerce growth rate during the quarter.

comScore said that multi-channel retailers regained e-commerce spending market share versus online pureplay retailers following five consecutive quarters of declining market share.

Consumer electronics (excl. PC peripherals), computer software (excl. PC games), computers/peripherals/PDAs, and books & magazines were among the top-performing online product categories.

Gian Fulgoni, chairman of comScore, said: "The second quarter’s continuation of the first quarter’s strong retail e-commerce growth rates is encouraging.

"We remain cautiously optimistic heading into the second half of the year, but we will be keeping a close eye on unemployment rates, which along with potential uncertainty in the stock market could limit growth in e-commerce spending in the near term."