IDG News Service — Microsoft's Bing overtook Yahoo Search in only its fourth day of public release according to Web analytics company StatCounter, but it's too soon to tell how well the new search engine will fare in the long run.

On Thursday, Bing became the No. 2 search engine in the U.S. and worldwide, with 16.28 percent share of searches to Yahoo's 10.22 percent in the U.S., and 5.62 percent for Bing to 5.13 percent for Yahoo worldwide, according to StatCounter. StatCounter's Global Stats research data is based on 4 billion pageloads per month.

In a press statement StatCounter CEO Aodhan Cullen noted that it could be "initial novelty and promotion" that is giving Bing momentum, but said that Microsoft could be successful far sooner than it expected in achieving CEO Steve Ballmer's goal to be the No. 2 search engine within five years.

Microsoft released Bing on Monday, two days earlier than expected. The company is promoting the search engine as a "decision engine" aimed at helping people better organize search information and find what they're looking for more quickly, and has poured between US$80 million and $100 million into a marketing campaign to promote it. That campaign even included sending a blue "search" beam of light out from Seattle's famous Space Needle landmark on Tuesday above a launch party below, where the word "Bing" was spelled out in lights on a lawn. Microsoft is headquartered in Redmond, Washington, just outside of Seattle.

Forrester Research analyst Shar VanBoskirk said the early numbers are in no way indicative of how Bing will do against what she calls "the big two" of search -- Google and Yahoo -- in the long term. "I don't know that three days in it's reasonable to say that Bing has won the race," she said.

However, because Bing is similar to Yahoo in its approach to search, it makes sense that it would take share away from Yahoo before it would Google's search engine, VanBoskirk said.

"Bing is a greater threat to Yahoo than to Google because Yahoo has been sort of the content search engine and Google has been the utility search engine," she said.

In other words, Yahoo has taken more of a "concierge approach" to search, organizing its search results more based on what information other users have found useful in the past and based on services that can be offered around a search result, VanBoskirk said. This gives Yahoo's results more of the feel of a traditional Web portal than merely providing people with a list of relevant searches. Google, on the other hand, is more of a toolbar, she said.

"With Google's utilitarian approach and Bing and Yahoo being the more portal-based approach, it's easier to think why they would be more competitive," VanBoskirk said.