Looks like Best Buy’s got a pretty massive boner for Carphone Warehouse, as it’s just increased its ownership share from 2.9% to 50%, according to IDG News Service.

Best Buy has agreed to invest an additional $2.1 billion in the European retailer, likely by the end of August.

Carphone Warehouse will be opening stores here in the states this year and Best Buy is planning to open its first store in the UK in 2009. It appears that these kind of partnerships will be Best Buy’s main method of gaining access to foreign markets, as it’s also recently formed similar alliances with Future Shop in Canada and Jiangsu Five Star Appliance in China.