HELSINKI: Microsoft Corp on Tuesday said it would buy Nokia’s mobile phone business for 5.44 billion euros ($7.2 billion), and the Finnish firm said its CEO, Stephen Elop, would join Microsoft when the transaction closed.

Finland’s Nokia, once the undisputed leader in mobile phones, has been struggling to respond to the challenge from smartphone makers such as Apple and Samsung .

Analysts say Elop’s bold bet in 2011 to adopt Microsoft’s untested Windows Phone software has yet to pay off.

The deal is expected to close in the first quarter of 2014 and is subject to approval by Nokia’s shareholders and regulatory approvals. Nokia partnered in 2011 with Microsoft and uses Microsoft’s Windows software to run its mobile phones.