Microsoft is adding 433 million people to its professional network after agreeing a deal to buy LinkedIn for $26 billion.

The shock deal, which will be Microsoft's largest ever, sent LinkedIn's share price up by 50%.

Announcing the takeover, LinkedIn and Microsoft said the professional network's boss Jeff Weiner would remain in charge, while reporting to Microsoft chief executive, Satya Nadella.

Mr Nadella said: “The LinkedIn team has grown a fantastic business centered on connecting the world’s professionals.

“Together we can accelerate the growth of LinkedIn, as well as Microsoft Office 365 and Dynamics as we seek to empower every person and organization on the planet.”

Mr Weiner said: “Just as we have changed the way the world connects to opportunity, this relationship with Microsoft, and the combination of their cloud and LinkedIn’s network, now gives us a chance to also change the way the world works.

"For the last 13 years, we’ve been uniquely positioned to connect professionals to make them more productive and successful, and I’m looking forward to leading our team through the next chapter of our story.”

The biggest surprise of this deal is the size of Microsoft's bid, especially given that LinkedIn has lost more than half of its value over the past year following warnings that its key areas were witnessing slowing growth.