Android devices accounted for 75 percent of smartphone shipments during the three months ending in September, up from 58 percent at the same time in 2011, according to the research firm IDC. The iPhone's share stood at 15 percent in September, up from 14 percent in the previous year.
Google says more than 500 million Android devices have been activated since the software's release four years ago. By comparison, Apple had sold about 271 million iPhones through last September.
Apple could fall further behind as it focuses more on markets outside the U.S. and Europe. That's because many households in some of the most promising markets can't afford iPhones at their current prices.