Nielsen has released some smarpthone market share figures for March. The metrics firm says that 50.5% of US mobile phone owners now carry smartphones. The data show the following breakdown by operating system:
Here's comScore's March data for comparison purposes:
Comscore puts smartphone penetration at 45.2% in the US by comparison.
There's a meaningful difference in the numbers in terms of Android and iOS market share percentages in both data sets. In addition Nielsen shows 5.8% penetration of Windows, while comScore shows 3.9%. That's also a fairly significant difference.
They both agree however that the Windows Phone platform so far hasn't moved the needle and Microsoft's overall share of the smartphone market is declining.