IE11 is as secure as Chrome when used as a regular user with UAC enabled (on Win8, even moreso when running in an AppContainer or with EPM enabled). However, given the prevalence of folks who use admin accounts, this reduces security somewhat (of all browsers, but we're talking about IE here). IE's SmartScreen blocks more malware and other malicious content than other browsers, Chrome included, and most exploits nowadays for browsers affect Chrome just as much as they affect IE on Windows, because they exploit things other than the browser to get AT the browser.
With the advent of IE11 and Windows 8, Chrome is no longer the most secure browser, and most certainly not even on par until it can run inside an AppContainer process in both modern and desktop mode as well. Using an Untrusted integrity level (when IE uses low, by default, when not run with EPM enabled) does make it slightly more secure in it's default configuration on older platforms with IE10 or lower, for example when comparing it against IE9 on Vista, or IE10 on Win7 or Win8, but IE11 with EPM enabled should even the tables on Win7, and make it more secure on Win8 (because it uses the Win8 AppContainer integrity level, rather than low, not to mention all the other antimalware stuff that's built in).
