Microsoft's Internet Explorer (IE) continued to lose market share in September, while Google's Chrome stabilised at under 1 percent and more than half of Firefox 2.0 users accepted an offer to update to Version 3.0, a web metrics firm has revealed.

For the seventh month this year, and the second consecutive month, Internet Explorer (IE) lost ground in the battle for browser market share, Net Applications reported. During September, IE accounted for 71.5 percent of the browsers used to connect with 40,000 sites that the vendor monitors, down from August's 72.2 percent.

IE's share is down 4.5 percentage points since the first of the year.

Net Applications attributed part of September's IE decline to the introduction of Chrome, which Google launched early last month as a beta for Windows XP and Vista.

Even though Chrome came out of the gate strong - it garnered a 1 percent share within hours of its debut - it has faded somewhat since then. According to Net Applications, Chrome's share has stabilised at about 0.7 percent, just slightly more than Opera ASA's flagship, which had previously held down the number 4 spot, behind IE, Mozilla's Firefox and Apple's Safari.

Also down for the month was Firefox, which lost market share for just the second time in 2008. By the end of September, Firefox accounted for 19.5 percent of all browsers, off from August's 19.7 percent.

However, Mozilla's offer to automatically update users of the older Firefox 2.0 to the newer Firefox 3.0 was a success, said Net Applications. It measured a major shift from Firefox 2.0 to 3.0 after 25 August, when the company began the program.

Since late August, 51 percent of those using Firefox 2.0 have switched to the new Firefox 3.0, said Vince Vizzaccaro, Net Applications' executive vice president of marketing. While Firefox 2.0 owned 11.5 percent of the market and Firefox 3.0 accounted for 7.7 percent in August, last month the versions' position had flipped: In September, Firefox 2.0 had only 5.8 percent of the market, while Firefox 3.0 owned 13.3 percent.

Other Net Applications data showed that September marked the first time that IE6's market share fell under 25 percent, while Safari's part of the market climbed to 6.7 percent. Safari was the only major browser to boost its share last month, something that Vizzaccaro had earlier attributed to the lack of a Mac OS X edition of Chrome.

Microsoft's newest browser, IE8, also posted gains as it increased its share from 0.22 percent to 0.37 percent. The browser's second beta launched 27 August.

Net Applications' browser share and trend data is available online.