Here is the browser market share for September 2013, based on traffic to my top site (number in parentheses shows change from August 2013):
Google Chrome: 42.18% (+0.60%)
IE: 27.71% (-1.01%)
Firefox: 23.64% (+0.47%)
Safari: 2.98% (-0.30%)
Opera: 1.12% (+0.06%)
Our numbers showed that Google Chrome widened its lead in September, while IE lost significant ground. Interestingly, this is different from what StatCounter reported. On its website, StatCounter showed that Chrome dropped by almost 2% in September, while IE gained 3%.
The significant development in the browser world has been the most recent zero-day attack on IE, as well as the subsequent release of the exploit code into the wild. All versions of IE were affected. Microsoft offered a temporary patch to fix this problem. However, not all IE browsers were patched, and reportedly hackers are having a field day attacking the unpatched browsers. This type of news will surely send more people from IE to Chrome or Firefox.