Nokia's share of the smartphone market has fallen by a third, while Microsoft's has nearly halved, according to research firm Gartner.
The pair signed a deal earlier this year that has seen Nokia drop its Symbian OS in favour of Microsoft's Windows Phone 7, but no handsets have been released yet.
According to Gartner, Nokia's Symbian was running on 44.2 percent of all new smarpthones sold around the world in the first quarter of 2010. A year on, Symbian's share has fallen to 27.4 percent.
Microsoft saw a similar decline, sliding from a 6.8 percent market share of newly sold handsets, regardless of manufacturer, to 3.6 percent in the first quarter of this year - despite the launch of its new operating system Windows Phone 7.
Windows Phone saw only modest sales that reached 1.6m units in the first quarter of 2011.
It's not all bad news, as despite the drop in share, the global smartphone market as a whole doubled in actual units sold.
That means Symbian actually ended up on more new smartphones this quarter than the same time last year, with 28 million sold, while Microsoft held steady at 3.6 million globally, propped up by its older Windows Mobile OS.
"Windows Phone saw only modest sales that reached 1.6m units in the first quarter of 2011, as devices launched at the end of 2010 failed to grow in consumer preference and communications service providers continued to focus on Android," Gartner said.
The deal between Nokia and Microsoft, which will see Windows Phone on the manufacturer's handsets, will likely boost that OS, the analyst firm said. "In the long term, Nokia's support will accelerate Windows Phone's momentum," Gartner said.
Android's growth was notable, jumping from 9.6 percent market share last year to 36 percent of all smartphones sold in the first quarter of this year.
In the first quarter of 2010, that added up to 5.2 million smartphones; this year, that topped 36 million globally.
Meanwhile, Apple's iOS gained 1.5 points to 16.8 percent, but that slight gain in share translated to doubling sales of the iPhone to 16 million this quarter. RIM slid seven points to 12.9 percent, selling 13 million handsets.