No 10 'very concerned' over Facebook data breach by Cambridge Analytica

Downing Street backs information commissioner inquiry into data-mining affecting millions of people

Downing Street has expressed its concern about the Facebook data breach involving the analytics company that worked with Donald Trump's campaign team and that affected tens of millions of people.

No 10 weighed in on the row as almost $20bn (14bn) was wiped off the social network company's market cap in the first few minutes of trading on the Nasdaq stock exchange, where Facebook opened down more than 3%. By midday, the company's share price losses had multiplied to more than $40bn, making the day its worst in more than five years.