Microsoft is buying the professional networking site LinkedIn for more than AU$35 Billion.  The deal could reinvigorate the software giant's slipping grip on corporate computer systems and employee interactions.

"I have been thinking about this for a long time," said Microsoft chief executive Satya Nadella, revealing his interest in the purchase.  The deal was "key to our bold ambition to reinvent productivity and business processes", he added.

Buying LinkedIn means Microsoft will control the best-known network where companies and employees – especially potential employees – interact.

"That's a valuable asset that can be deeply integrated with a number of Microsoft assets such as Office 365, Exchange and Outlook," said Ben Wood, head of research at CCS Insight.  "That said, Microsoft has stated that the company will continue to operate as an independent business, so we'll have to see how deeply the integration occurs."

"Today is a re-founding moment for LinkedIn," said the company's Reid Hoffman - the chairman, co-founder and controlling shareholder of LinkedIn Reid Hoffman.  "I see incredible opportunity for our members and customers and look forward to supporting this new and combined business."

Past acquisitions haven't worked out too well for Microsoft, which has written down practically all of the US$9.5 billion it paid for Nokia.  In 2012, it wrote off nearly all the $6.3 billion shelled out for digital-advertising agency aQuantive.