For the second time just over a month ago, StatCounter Global Stats, which analyzes Web site traffic, reported that the new search engine's market share has passed that of the Yahoo search tool. According to the StatCounter report released today, Bing held a 12.9% share of the U.S. search market, while rival Yahoo held 10.15% at the start of July.

Both Microsoft and Yahoo are still well behind market behemoth Google, which commands just about 75% of the market, according to the report.

The traffic tracker had reported last month that on one day shortly after its June 1 launch.

Aodhan Cullen, CEO of StatCounter, said in a statement that the latest figures may have resulted from a positive review of Bing that appeared on the New York Times Web site on July 8 and in its print edition a day later. "While its lead over Yahoo may not last into next week, our data suggests that it is slowly but surely closing the gap."

Meanwhile Hitwise Pty., which measures online traffic, released a report yesterday showing that Bing's market share, while growing, still trails far behind Yahoo.