Firefox continues to gain market share at the expense of Microsoft's once-dominant but increasingly insecure Internet Explorer browser.

While the pace of Firefox growth has slowed down slightly, Internet Explorer's market share has dropped beneath 90 per cent according to figures from both WebSideStory and

As of February 18, Firefox held a 5.7 per cent share of the US browser market and IE stood at 89.9 per cent, according to WebSideStory. In November, right before the Firefox 1.0 launch, IE held 92.9 per cent of the market and earlier versions of Firefox held 3.03 per cent, according to WebSideStory.

According to Firefox now holds 8.45 per cent of the browser market on a worldwide basis, while Microsoft's IE continues to dominate with an 87.28 per cent share, down 1.62 per cent compared with the end of November.

Firefox's market share gains have slowed slightly: they grew 15 per cent over the last five weeks, compared to growth of 22 per cent in the period between December 3 and January 14. From November 5 to December 3, right after the launch of Firefox 1.0 on November 9, the browser's market share grew 34 per cent, it said. (Though this fast-paced adoption took place after a widespread and well-recieved mass beta test).

The initial high adoption rate had Firefox on a path to reach a 10 per cent market share by mid-2005, the slight slow down still means the browser is likely to grab 10 per cent of the market by year's end. That achievement would be in line with the goal set by the Mozilla Foundation.

"Growth in Firefox’s usage has slowed slightly since its big surge in November. This is probably to be expected as we move beyond the early-adopter segment," WebSideStory CEO Jeff Lunsford said. "Growing concern over potential security holes in the browser might be another factor to consider."

The Mozilla Foundation, the distributor of Firefox, last week warned of serious security flaws in the browser and released an update. In an about face two weeks ago, Microsoft said it would release a test version of IE 7.0 in mid-2005. Previously, Microsoft had said it would not offer a browser upgrade until the next version of Windows ships in late 2006.