Nokia is being sued by one of its investors, Robert Chmielinski, over its decision to adopt Windows Phone OS as its primary smartphone platform. Chmielinski filed a securities class action complaint on 3 May 2012 with the US District Court for the Southern District of New York, naming the Espoo-based cellphone giant as a defendant.

The finnish firm revealed back in February last year that it was boarding Microsoft’s Redmond-powered mobile operating system (OS) train, opting to make Windows Phone OS its primary smartphone OS on forthcoming devices. Since that time the company has announced and released quite a few Windows Phone Mango-running devices such as the Nokia Lumia 800, Lumia 900, and Lumia 710.   

Although these devices have put the Finnish giant back on the smartphone map and provided it with a mobile platform to take on the iPhone’s iOS and the Android-operating competition, these haven’t exactly set the smartphone sales charts on fire.

Within its latest fiscal term (Q1 2012), the company only sold 12 million smartphones, compared to Apple’s 35.1 million iPhones and the new top global mobile phone vendor Samsung’s 42.2 million mobile devices. What’s more is that only two million out of the twelve million smartphones sold were Windows Phone OS-powered Lumia devices.

The complaint states that: “During the Class Period, defendants told investors that Nokia’s conversion to a Windows platform would halt its deteriorating position in the smartphone market. It did not. This became apparent on April 11, 2012, when Nokia disclosed that its first quarter performance would be worse than expected.”

“It also disclosed a glitch in its newest Windows Phone offering - the Lumia 900. Nokia had to immediately offer customers an automatic $100, making the phone essentially free. As a result of this disclosure, the price of Nokia’s American Depositary Shares ("ADRs") dropped over 16% in a single day.”

Nokia stated that it is reviewing the allegations contained in this complaint and believes that these have no merit. The company also stated that it will defend itself against the complaint.

In related news, Nokia recently announced that it has filed patent claims in the US as well as Germany, via which the company alleges that products from HTC, BlackBerry holding company RIM (Research In Motion) and Viewsonic infringe upon a number of its patents. The Finnish firm didn’t specify which of these companies’ products are infringing upon its patents.