Here is the browser market share for May 2014, based on traffic to my top site (number in parentheses shows change from April 2014):
Google Chrome: 49.83% (+1.58%)
IE: 22.50% (-1.24%)
Firefox: 21.17% (-0.08%)
Safari: 3.31% (-0.03%)
Opera: 0.78% (-0.11%)
The big news in May was the 1.24% drop in IE’s market share. The most likely reason was the zero-day vulnerability discovered in April and the subsequent press coverage (including the one from US CERT). We had predicted that IE’s market share would dip by at least 0.5% in May, and IE’s loss turned out to be more than that.
Google Chrome was the biggest winner in May, as it was now approaching 50% in usage. All other browsers showed a decline, although the decline was relatively small outside of IE. It is worth mentioning that Android browser had a 0.84% share in May, higher than that of Opera.