E-commerce activity rose 2% in January, according to one widely watched measure, offering a glimmer of hope for Internet retailers such as eBay Inc. (EBAY) and Amazon.com Inc. (AMZN) even as industry insiders say the sector has yet to put the worst behind it.

Market research group comScore said online sales rose in January largely because middle-class consumers went bargain-hunting. The monthly data follows comScore's report last week that fourth-quarter retail e-commerce sales fell 3% from the same period a year earlier, marking the first quarter of negative growth since the company began tracking spending in 2001.

"I have my fingers crossed that we might well have reached the bottom," comScore Chairman Gian Fulgoni said in an interview. The company was scheduled to present its data in a conference call at noon EST Thursday.

ComScore's data comes after the biggest e-commerce companies reported mixed earnings for the quarter ended Dec. 31. Amazon, which said the holiday season was its best ever, reported an 18% surge in fourth-quarter sales despite the difficult market conditions. EBay reported its first-ever quarterly revenue decline.

Despite comScore's data, many industry insiders and observers say the $130 billion U.S. e-commerce market is likely to get worse before it gets better.

"We can expect really tough times ahead for a number of months, easily through the first half of the year," said eMarketer e-commerce analyst Jeffrey Grau. "I don't see signs of improvement."

The conflicting outlooks come amid a sharp slowdown in the economy that hammered consumer spending both online and through traditional retail outlets during the fourth quarter. Last week, the U.S. Commerce Department said overall retail sales staged a surprise 1% rebound in January as stores cut prices. It was the first month-to-month gain after six straight months of declines, but economists cautioned that sales could slip again as consumers cut spending.

In addition to fueling the performance of online shopping sites, the health of the e-commerce sector is important to top online advertising companies. Market leader Google Inc. (GOOG) said its fourth-quarter advertising revenue held up fairly well because retailers had stocked a lot of holiday inventory and consumers flocked online to search for the best deals. But last month, company executives said they were concerned the dynamic may have played itself out going into the first quarter of 2009.

"One of the things we have to ask ourselves now is how much of that inventory has actually flowed through the system," said Jonathan Rosenberg, Google's senior vice president for product management. "Obviously, we would be adversely impacted if it was less total commerce moving through."

Shares of e-commerce and online advertising companies have been hit since the economic turmoil began weighing on markets.

Early Thursday, Amazon, whose shares had dropped more than 30% from their 52-week high, were up 0.7% at $62.82. Ebay, down more than 60% from its 52-week high, was down 1.8% at $12.27. Google shares, off more than 40% from a 52-week high, were down 1.5% at $347.68.

Few industry participants believe e-commerce activity has bottomed out. Scot Wingo, chief executive at e-commerce software maker ChannelAdvisor Corp., said the value of Internet retail sales processed by his company's software in January was flat from the same period last year. That compares with a 2% increase in the fourth quarter and suggests the downward momentum in sales has continued into early 2009.

Barclays Capital analyst Doug Anmuth said in a note earlier this week that checks with search engine marketers indicated shoppers and advertisers immediately pulled back spending in early January.

Anmuth's conclusion was echoed by search engine marketer Reprise Media, which told Dow Jones that spending on Internet search terms by its e-commerce customers was down about 10% in January compared with December.

Reprise, a subsidiary of ad giant Interpublic Group of Cos. (IPG), also said online consumers are comparison shopping to a far greater degree than they used to, which points to an e-commerce market that continued to soften in the first month of 2009.

-By Scott Morrison, Dow Jones Newswires; 415-765-6118; scott.morrison@dowjones.com