Google's Android was the top smartphone OS on Millennial Media's mobile ad network for the sixth consecutive month, capturing 53 percent of all ad impressions in May, according to a new report.
In second place, Apple's iOS shed a single percentage point from, grabbing 27 percent of all ad impressions in May. That left BlackBerry maker Research In Motion with a 17 percent share, up slightly from the prior month thanks to demand for its BlackBerry Curve, according to Millennial Media, which says it tracks ads on more than 85 percent of all mobile devices in the U.S.
Nokia's Symbian and Microsoft's Windows Phone trailed with 2 percent and 1 percent of all ad impressions, respectively.
Looking at the mobile device makers specifically, Apple remained in first place among the top 15 mobile device makers with 30.8 percent of all ad impressions, a figure that included the iPhone, iPad, and iPod Touch.
The iPhone alone took home a 16.5 percent share among the top 20 mobile phones, giving it the lead among all phones for the 20th month in a row, according to the report. But the iPad also boosted Apple's standing, with ad impressions for the popular tablet growing 29 percent over April.
In second place among the top 15 device makers, Samsung accounted for 13.5 percent of all impressions, while RIM trailed closely with 13.3 percent. For May, HTC moved up to fourth place and accounted for almost 11 percent of all ad impressions.
For the first time, Millennial Media also looked at what types of Net-connected devices are hitting its network, other than mobile phones. Mobile gaming devices and MP3 players grabbed 70 percent of all ad impressions in that category, while tablets captured the remaining 30 percent. But the company expects tablets to continue to chew up a greater share of impressions as their adoption increases.
Overall, smartphones accounted for 67 percent of all add impressions, with feature phones scooping up 17 percent and Net-connected devices taking 16 percent.