Facebook buys messaging app WhatsApp

Facebook has announced that it will buy messaging app WhatsApp in a deal worth $19bn (£11.4bn) in cash and shares.

It's Facebook's biggest ever acquisition - and will give it access to 450 million people who use WhatsApp every month.

In a statement announcing the deal, Facebook founder Mark Zuckerberg described the acquisition as "incredibly valuable", but Facebook's share price dipped following the announcement.

Rory Cellan-Jones reports.