• by Sarah Mahoney  @mahoney_sarah, August 10, 2011

While online sales are booming, jumping 14% in the second quarter to $37.5 billion, turmoil in the financial markets is already having a significant impact on consumer sentiment.

"Consumer perceptions of the economy had been improving moving into August," comScore chairman Gian Fulgoni says in a webcast to present the company's latest research. "But our latest shows a major change. Between the end of July and our polling this week, the number of Middle Americans rating the economy as poor jumped to 64%, from 58%."

He adds that among Middle Americans, which it defines as those earning between $50,000 and $99,999, unemployment and job security was the chief economic concern in July. But by this week, worries about the financial markets nearly doubled to 36%, from 21%.

"We are dealing with a very fragile consumer in terms of sentiment," he says. "And it is also true the media is exacerbating the sentiment with a continuous flurry of updates, causing consumer concerns to bounce around. Consumers are getting buffeted by this wave of economic news, much of it not positive."

Online spending continues to be robust. This quarter's gains are the seventh consecutive quarter of positive year-over-year growth, as well as the third consecutive quarter of double-digit growth rates, well ahead of consumers' overall spending.

"The recession didn't take as big a bite out of online as it did out of retail," he says. "As we come out of the recession, we've got growth in both overall spending and online, and online is higher. That trend seems to be accelerating." Almost one of every ten discretionary dollars is now spent online, he says.

The lower-income segment continues to show the strongest year-over-year rebound from the recession.

Consumer electronics, including computer hardware and software, and event tickets, are among the strongest-selling categories.

ComScore bases its figures on its global panel, which includes 2 million Internet users, with 1 million in the U.S. (It excludes travels, autos and auctions.)