Google's Chrome's share also climbed in April, said Net Applications, ending that browser's .
IE boosted its share by about three-tenths of a percentage point last month to average 54.1% in April. That returns IE to a mark comparable to its September 2011 share.
Since Jan.1, IE has increased its usage share by 2.2 percentage points for a 4% gain since the end of 2011. The turnaround has been IE's largest and longest since the browser began shedding share years ago to Firefox, then later, Chrome.
Microsoft has pinned its hopes almost entirely on IE9, the 2011 edition that runs only on Windows Vista and Windows 7.
On Tuesday, Microsoft again stayed on message, highlighting the -- the pairing the firm has said is the only metric it cares about -- but ignoring the overall IE increases this year.