Apple's iOS gained a 5 percent market share lead over Android and now accounts for 62 percent of mobile ad impressions (compared to Android's 38 percent), a report claims.

Velti, a provider of mobile marketing and advertising technology, also reports that just under half of all iPhone 5 impressions came from the U.S., followed by Japan with 14 percent, and the UK with eight percent of impressions.

Additionally, Velti data reveals that, although iOS 6 saw quick adoption among a large amount of users, 11% of users have opted not to upgrade to the operating system and remain using iOS 4.

"In July and August, Android held prevalent market share in a year that was previously dominated by iOS?but September marks an end to this trend," said Krishna Subramanian, CMO of Velti. "We are seeing a pattern that leads us to believe the shift back to iOS domination is a result of the iOS 6 release and iPhone 5 launch. In fact, this is similar to the change we saw directly after the iPhone 4S release, when iOS volume also spiked by five percent."

Velti's September report also reveals insight into engagement patterns of iPhone 5 early adopters. Consumers were eager to try out their favorite apps on their new devices - Velti's data shows consumers spent 27 percent of their time on social networking applications, followed by games (22 percent) and entertainment and utility apps (13 percent each).

Despite Apple's prevalence in the U.S. and excitement around the iPhone 5 launch, other regions are not necessarily following suit. The new Velti data shows that Samsung is the clear leader in its home market of Korea, and it is the #1 smartphone, with a sizeable margin, in impression share there. Apple?s devices are relegated to the third and fifth places in the country (iPhone 3 and iPhone 4 respectively).

Other notable data from the report includes:

- Samsung's Galaxy S III: Samsung?s Galaxy S III entered the top five devices on the exchange this month, capturing 1 percent of all impressions.
- AT&T leads U.S. carriers with over half of all iPhone impressions. Verizon comes in second with just under a third of impression volume.
- Weather Surge: Weather is once again the leader on the eCPM Index, after being beaten by Education apps in August.

Velti's full report is available here.