Smartphone shipments fell annually and Android actually lost ground to Apple’s iOS, according to a new report from Strategy Analytics. 

Smartphone shipments fell 5 percent annually to reach 24 million units in the United States during the second quarter of 2012.

Android’s market share fell four percentage points on an annual basis to 56 percent.

Strategy Analytics estimates that 13.4 million Android smartphones shipped during the second quarter for 56 percent share of the U.S. market. That’s down from 15.3 million units shipped with a 61 percent market share a year earlier. 

Android remains the number one platform by volume in the United States, but its market share is approaching a peak and Apple iOS has been gaining ground. 

“This was one of the slowest growth rates ever experienced by the important U.S. smartphone market,” wrote Alex Spektor, associate director at Strategy Analytics, in the report. 

Spektor attributed the drop in shipments to a volatile economy, maturing penetration of smartphones among contract mobile subscribers and major operators tightening their upgrade policies to enhance profits. 

According to the report, Apple’s U.S. market share has risen by ten points from 23 percent in the second quarter of 2011 to 33 percent in the same quarter of 2012. 

“Apple is rumored to be launching a new iPhone in the coming weeks, and that event, if it takes place, is going to heap even more pressure on Android in its home market,” wrote Neil Mawston, executive director at Strategy Analytics. 

The numbers could reassure investors who backed off Apple stock last week as the company reported lower than anticipated iPhone sales due to customers awaiting the new model.