The share of recent smartphone buyers in the United States who chose Apple’s iPhone over rivals in the fourth quarter nearly doubled compared to the three months ending in October 2011, Nielsen said on Wednesday. The market research firm polled recent smartphone acquirers in December and found that 44.5% of buyers purchased an iPhone over the three months leading up to the survey. Meanwhile, 46.9% of respondents said they purchased an Android smartphone and 4.5% said they bought a BlackBerry. A similar poll conducted in October found that 25.1% of recent acquirers purchased an iPhone compared to 61.6% who purchased an Android phone and 7.7% who chose a BlackBerry smartphone. Nielsen also noted that among recent smartphone buyers between October and December who purchased an iPhone model, 57% bought an iPhone 4S. In the fourth quarter, Nielsen found that Android held its OS market share lead with 46.3%, followed by iOS (30%), BlackBerry OS (14.9%), Windows Mobile (4.6%), webOS (1.4%), Symbian (1.4%) and Windows Phone (1.3%). Additional charts highlighting Nielsen’s findings follow below.