Facebook chief executive Mark Zuckerberg has lost almost US$7 billion ($A9.6 billion) from after his social media empire crashed early on Tuesday – prompting investors to sell off Facebook stock.

Facebook shares fell by as much as 6 per cent to US$323 on Tuesday morning (Australian time) as the company deployed engineers to fix a botched update that sent Facebook, Instagram and WhatsApp offline.

It meant Mr Zuckerberg, who owns 14 per cent of Facebook, fell to fifth spot on Bloomberg’s list of the world’s richest people, with a personal wealth of about US$122 billion ($167 billion).

Just hours earlier the tech executive was worth as much as $176 billion.

If those losses were liquid they could buy more than 10,000 houses in Sydney or pay for Australia’s entire COVID vaccination rollout to date.

Facebook itself lost more than $700,000 in advertising revenue for every hour its websites were down, based on its annual sales data.

Don’t feel bad for Mr Zuckerberg though. Facebook’s stock has already begun to recover from the fall and is still up 21 per cent since January 1.

Security experts tracking the event said the Facebook outage might have been triggered by a configuration error, which could be the result of an internal mistake, although sabotage could not be ruled out.

Downdetector – which tracks outages by collating status reports from a series of sources, including user-submitted errors on its platform – showed there were more than 50,000 incidents of people reporting issues with Facebook and Instagram.

Facebook has had similar widespread outages with its suite of apps this year in March and July.

It is also just the latest controversy for Facebook, which has been under pressure lately over a series of articles published by The Wall Street Journal – a paper owned by billionaire Amazon founder Jeff Bezos – about misinformation on Facebook and its impact on user mental health.

Since those articles began being published Mr Zuckerberg’s wealth has plunged from an annual high of $195 billion in September to $167 billion.

That is a $28 billion loss, enough to pay for Australia’s vaccination rollout more than three times over and still have enough left to buy a hospital.

-with AAP