According to data compiled by WebSideStory, a Web measurement supplier, Internet Explorer's market share has dropped 1.32 percentage points since June 4, the first marked decay in its market leadership since 1998.
"Sometimes these are just spikes," said Geoff Johnston, an analyst with WebSideStory, "but this has become a very predictable trend."
Internet Explorer has had more than 95% of the browser share for the past two years, and until early June, had owned about 95.7% of the market. Within the last month, however, Internet Explorer's share of the U.S. browser market fell from 95.48% on June 4 to 94.16% on July 9.
Netscape and Mozilla saw their share climb from 3.54% to 4.59%. (WebSideStory tracks Netscape and Mozilla as a single unit, and in its count also includes Mozilla's standalone Firefox.) The 'All Others' category, which is primarily Apple's Safari browser with a bit of Opera thrown in, also got a boost, rising from 0.97% in June to 1.24% in July.
"The past couple of years, IE's share has been pretty steady. But this is the first time we're seeing an actual trend," said Johnston.
A 1.32 percentage point loss may not set alarm bells ringing at Microsoft, but when one considers how many people use the Internet, the number of users switching are significant. "If you're looking at the overall pie, it's not big deal, but from another angle, the size of the switch is substantial," said Johnston.
Some analysts estimate the U.S. Internet population at around 200 million. A 1.32 percentage point change in browsers, then, translates into 2.6 million users who've dropped Internet Explorer.
The slip is also important, said Johnston, simply because it's so difficult to get people to change browsers. Any change is news. "There's this huge inertia," he said, "that keeps them using the same browser."
Behind the downturn in Internet Explorer's share, said Johnston, is the combination of its recent slew of security problems and the appearance of alternatives that are as good, or in some cases better, than Microsoft's browser.
"Millions of people were just waiting for an excuse to change," he said, referring to a pent-up desire on the part of some to move away from Microsoft's monopoly. "It wasn't going to take that much to convince them. The security problems [of IE] mixed with the launch of excellent alternatives, like Firefox, are what's finally getting people to switch. I don't think that just one of those would have done it."
Internet Explorer has been the target of several exploits in the past weeks, including an innovative attack launched by Russian hackers that used an unpatched vulnerability to infect users' PCs with Trojan horses and keyloggers in the hope of stealing user account and financial data. Microsoft released a temporary fix on July 2, but it has yet to produce a permanent patch.
Reacting to Internet Explorer's continued security issues, numerous analysts recommended that users steer clear of the Microsoft browser, at least until it's fixed. Among them: the U.S. Computer Emergency Response Team, the technology arm of the Department of Homeland Security.
When advice like that comes down the pike, said Johnston, and users start to switch, the balls starts rolling. "A little momentum gives people a lot of courage to change. They're thinking, 'I'm not the only one.' Like they say, nothing attracts a crowd like a crowd."
Even though Internet Explorer has experienced what WebSideStory sees as a significant decline, Johnston doesn't think the trend will go too far. "If Microsoft loses two or three points, I'd be surprised," he said. "Internet Explorer is, after all, their Holy Grail."