Neck and neck and neck for iOS, BlackBerry and Android, but the latter has the momentum.
iOS has consolidated its lead over BlackBerry for US smartphone OS share, but Android is coming up fast, according to the latest research from Nielsen.
The company says iOS had a 28.6% share of adult smartphone consumers in November, the same as its share in September when it overtook BlackBerry for the first time.
BlackBerry fell from a 28.3% share to 26.1% in the same period, while Android rose from 21.9% to 25.8%.
A statistical curiosity: due to the margin of error, BlackBerry is 'statistically tied' with both iOS and Android, even though they're not tied with one another.
Android appears well-placed to overtake both its rivals early this year - if it hasn't already. According to Nielsen, in the six months to November, 40.8% of new smartphone sales were Android devices, versus 26.9% that were iPhones and 19.2% that were BlackBerries.
Overall, 45% of people who bought a mobile phone in the US during that six-month period chose a smartphone.
As ever, the caveat to these smartphone stats is that they do not include sales of other devices running these operating systems - the iPod touch and iPad for Apple, and the first wave of Android tablets for Google's OS.
For more on Nielsen's research, click here.