Facebook lost $US119 billion in value overnight, among the biggest single-day falls in US stock market history.

That is nearly the entire market value of corporate giants like McDonald's, Nike and IBM.

The 19 per cent drop in Facebook's share price (to $US176.26) marked the social media giant's worst trading day since it went public in 2012.

As a consequence, the personal fortune of Facebook's chief executive Mark Zuckerberg fell about $US15 billion to about $67 billion, according to Forbes.

Facebook's bad day in comparison

Corporation Market value on NYSE McDonald's $US122 billion General Electric $US114 billion BHP Billiton $US126 billion IBM $US134 billion Nike $US125 billion Commonwealth Bank $US131 billion Rio Tinto $US96 billion Netflix $US158 billion (Source: Bloomberg)

The drop in Mr Zuckerberg's net worth is roughly equal to the wealth of the world's 81st-richest person — currently Japanese businessman Takemitsu Takizaki, according to Forbes real-time data.

Previous record-setting bad days on Wall Street include Intel shedding $US90 billion in September 2000 and Microsoft falling $80 billion earlier the same year. Adjusted for inflation, Intel's loss would equate to more than $US130 billion now.

This is because of privacy and the fake news fight

It occurred after Facebook executives predicted the company would face lower profit margins for more than two years, while reporting its quarterly results on Thursday.

That "bombshell" announcement, as one analyst described it, played into concerns that Facebook's business model could be under threat — after a year dominated by efforts to head off concerns over privacy and its role in global news flow.

Facebook's second-quarter results were the first sign that a new European privacy law and a string of privacy scandals involving Cambridge Analytica and other app developers were hitting the company's business.

Mr Zuckerberg himself noted during a call with analysts that "we're investing so much in security that it will significantly impact our profitability".

The company also warned that the toll would not be offset by revenue growth from emerging markets and Instagram, which has been less affected by privacy concerns.

Some analysts said Facebook's issues would not be easily resolved. "Unlike Netflix, whose quarterly shortfall we saw as temporary, here we see an evolution of the story, albeit a portion of which we expected," BMO Capital Markets analysts Daniel Salmon said.

Others, however, saw a silver lining in Facebook's emphasis on more engaging content and its promotion of stories on its News Feed, which would support revenue over the longer term.

"Mark Zuckerberg isn't panicking," media academic Siva Vaidhyanathan said. "The Facebook board isn't panicking. Most of its large institutional investors aren't panicking. They know they're in it for the long game."

Pulling down the stock market

Nevertheless, as one of America's biggest publicly-listed companies — with a total market value of around $US503 billion — any significant rise or fall in Facebook's share price has an impact on the broader market.

Its overnight plunge dragged the tech-heavy Nasdaq index down 1 per cent to 7,852 — its largest one-day drop in a month.

Markets at 7:10am (AEST): ASX SPI 200 futures +0.4pc to 6,224, ASX 200 (Thursday's close) flat at 6,245

ASX SPI 200 futures +0.4pc to 6,224, ASX 200 (Thursday's close) flat at 6,245 AUD: 74.8 US cents, 56.29 British pence, 63.39 Euro cents, 82.06 Japanese yen, $NZ1.09

AUD: 74.8 US cents, 56.29 British pence, 63.39 Euro cents, 82.06 Japanese yen, $NZ1.09 US: Dow Jones +0.4pc at 25,527, S&P 500 -0.3pc at 2,837, Nasdaq -1pc at 7,852

US: Dow Jones +0.4pc at 25,527, S&P 500 -0.3pc at 2,837, Nasdaq -1pc at 7,852 Europe: FTSE +0.1pc at 7,663, DAX +1.8pc at 12,809, CAC +1pc to 5,481 Euro Stoxx 50 +1.2pc at 3,509

Europe: FTSE +0.1pc at 7,663, DAX +1.8pc at 12,809, CAC +1pc to 5,481 Euro Stoxx 50 +1.2pc at 3,509 Commodities: Brent crude +0.6pc at $US74.37/barrel, spot gold -0.7pc at $US1,222.27/ounce, iron ore +0.4pc at $US66.30/tonne

Facebook's decline also weighed on the benchmark S&P technology index, which fell 1.7 per cent.

The benchmark S&P 500 index fell 0.3 per cent.

The second biggest drag on the market was online retailer Amazon (-2.9pc), another member of the so-called FANG group of momentum stocks (which also include Facebook, Netflix and Google).

However, industrial stocks rose after US President Donald Trump said he would hold further trade negotiations with the European Union — marking a de-escalation of the trade war on that front.

This sent the Dow Jones index rising 0.4 per cent to 25,527.

It also led to European markets ending their day with strong gains in Frankfurt (+1.8pc) and Paris (+1pc), though London rose slightly (+0.1pc).

Furthermore, the European Central Bank decided on Thursday (local time) to keep interest rates steady, and its monetary policy unchanged.

The ECB said it still plans to wrap up its lavish bond purchases by the end of the year and sees interest rates staying at record lows through the summer of 2019.