Apple's iPhone 4S was outsold by Samsung's Galaxy S III smartphone in the US for the month of August, pushing the Apple device down to second for the first time since it launched last October, reports Apple Insider.

However, analyst Michael Walkley with Canaccord Genuity says iPhone sales have been soft ahead of the iPhone 5 expected to be announced on September 12.

"We believe this is the first month since the iPhone 4S launched in October 2011 that it was not the top selling smartphone in the US market," wrote Walkley. "However, our checks indicated strong consumer interest and likely demand for the iPhone 5, and we believe Apple will return to strong number one smartphone share in the US post the iPhone 5 launch."

Apple sent out invites for its September 12 event yesterday.