Vista/IE market share slide, Win 7/Firefox/Chrome surge
According to data supplied by web metrics firm Net Applications, both Vista and Internet Explorer lost market share during September, while Windows 7, Firefox and Chrome all saw a surge in market share.
Context & Ripple Effects
Microsoft's erosion is a two-front story with a long arc: IE was already shedding ground back in January 2007 despite 100 million IE 7 installs, dipped below 70% of the browser market by November 2008, and saw users downgrading IE 8 back to Explorer 7 in March 2009. The September Net Applications numbers extend that slide rather than reverse it.
The notable twist this month is that the desktop OS line is moving in parallel with the browser line: the same dataset shows Vista losing share as Windows 7 surges, meaning Microsoft's own successor product is what's cannibalizing its current install base ahead of launch.
First-order effects
- Microsoft enters the Windows 7 launch window with both flagship franchises declining in the same measurement period — Vista losing OS share and Internet Explorer losing browser share per Net Applications.
- Firefox and Chrome capture the browser share IE gives up, continuing the gain pattern Firefox showed in March's share shuffle when Safari was the loser.
Second-order effects
- Chrome and Firefox are now both feeding off IE's decline, setting up direct competition between them for the anti-IE bloc rather than a simple two-horse race against Microsoft.
- Windows 7's surge makes default browser placement on new installs the decisive battleground — whoever ships as the out-of-box choice inherits the upgrade wave.
Third-order effects
- If the pattern holds, browser share decouples from OS share: owning the desktop no longer guarantees the browser, forcing competition on update cadence and standards compliance instead of distribution alone.
- Monthly web-metrics scorecards like Net Applications' become the de facto public scoreboard that shapes developer and press narratives between product launches.
The trend: Browser and operating system market share are decoupling, with Microsoft's twin franchises eroding simultaneously as lighter-weight rivals convert each IE retreat into their own gain.