Ascending mobile player Windows Phone is also one to watch, says IDC, almost trebling its share in the past year.
Ramon Llamas from IDC's Mobile Phone team, blames the iPhone slump - down 3.5% - on lack of new model in almost a year.
These stats come despite Apple recent results celebrating "record" shipments (of 37m) for Q2.
"Without a new product launch since the debut of the iPhone 5 nearly a year ago, Apple's market share was vulnerable to product launches from the competition."
However, rumours of a budget iPhone launch later this year could turn Apple fortunes around. "Apple is well-positioned to re-capture market share," says Llamas.
Other analysts agree.
"We believe a well-executed $200-$300 iPhone would sell double-digit millions of units - a significant challenge to Android and Google," said UK researchers Enders Analysis, yesterday. The move away from pricey phones would be a "defensive one", and would have a small impact on its bottom line.
Microsoft's mobile OS is also a rising star, and managed to capture almost 9% of the market in the second quarter.
Ryan Reith, IDC analyst says "Nokia has clearly been the driving force behind the Windows Phone platform and we expect that to continue. "