Announced late last year it's official now and the divestment of Sony Ericsson is completed. The previously announced divestment of Ericsson's share of Sony Ericsson to Sony, including the broad IP cross-licensing agreement, completed yesterday, on February 15, 2012. This makes the handset maker, formerly known as Sony Ericsson, now a wholly-owned subsidiary of Sony. The agreed cash consideration for the transaction is 1.05 billion Euro. Since Ericsson has officially left the join-venture, Sony has announced to rename Sony Ericsson to "Sony Mobile Communications", and further integrate the mobile phone business as a vital element of its electronics business.

Sony aims to accelerating convergence between Sony's lineup of network enabled consumer electronics products, including smartphones, tablets, TVs and PCs.
As of today, the Sony Mobile Communications headquarter will stay in London (UK) as well as Sony Mobile's R&D sites are expected to stay in Beijing (China)), Lund (Sweden), Silicon Valley (U.S.) and Tokyo (Japan)
Cheers ~ Arne