With few exceptions, Microsoft's share of the browser market has been steadily declining since at least November 2009, which is how far back Net Marketshare lets us look. Back then, Microsoft's Internet Explorer was the dominant browser on desktops with a 64.46 percent share. And today? It's still dominant with a 52.63 percent share of the market, but the gap is quickly narrowing.
At this point, it seems likely IE will eventually give up the lead, but to which browser? By the numbers, Mozilla's Firefox is the closest threat with a 22.51 percent share at the end of October, which is up slightly from 22.48 percent in September, but down from 25.05 percent in November 2009.
Google Chrome is where the smart money is at, at least if forced to pick an eventual winner today. Chrome has seen a greater than four-fold increase in usage since November 2009 when it held a 3.98 percent share, and with the exception of June 2010 to July 2010, has grown its desktop browser market share every single month. Chrome now accounts for 17.62 percent of all desktop browsers, an increase of 1.42 percentage points from one month prior.