According to The NPD Group (http://www.npd.com), a market research company, Android’s operating system (OS) share of smartphone sales grew to command more than half of the U.S. smartphone market (53%) from January through October 2011, as Apple’s iOS share grew to reach 29% of the market.

RIM’s OS share declined to 11%. RIM and other companies that were formerly on top of NPD’s smartphone rankings, however, have made critical business decisions this past year in a quest to shore up their U.S. smartphone businesses, according to NPD.

“The competitive landscape for smartphones, which has been reshaped by Apple and Google, has ultimately forced every major handset provider through a major transition,” says Ross Rubin, executive director, Connected Intelligence for The NPD Group. “For many of them, 2012 will be a critical year in assessing how effective their responses have been.”