The parent of social media giant Facebook has seen its shares nosedive on news the social media giant's daily active users has dropped for the first time in its 18-year history.
Meta Networks says daily active users (DAUs) fell to 1.929billion in the three months to the end of December - compared to 1.930billion in the previous quarter.
The US group also warned of slowing revenue growth in the face of competition from rivals like TikTok and YouTube, while advertisers are also cutting spending.
BBC reports that Meta's shares slumped by more than 20% in after-hours trading in New York.
The slide in Meta's share price wiped around £147.5billion off the company's stock market value.
Shares in other social media platforms, including Twitter, Snap and Pinterest, also fell sharply.
Chief executive Mark Zuckerberg said the company's sales growth had been hurt as audiences, especially younger users, had left for rivals.
Meta, which owns the world's second-biggest digital advertising platform after Google, also said it had been hit by privacy changes on Apple's operating system.
The changes have made it harder for brands to target and measure their advertising on Facebook and Instagram and could have an impact in the order of $10billion (£7.38billion) for this year, according to Meta's chief financial officer Dave Wehner.
Meta's total revenue, the bulk of which comes from advertising sales, rose to $33.67billion (£24.84billion) in the last quarter of 2021, narrowly beating market predictions.
It also forecast revenues of between $27billion (£19.92billion) to $29billion (£21.4billion) for the next quarter, which is lower than analysts had expected.
While the company has been making its own investments in video to compete with TikTok - owned by Chinese tech giant ByteDance - it makes less money from those offerings than its traditional Facebook and Instagram feeds.
FTSE 100
The main focus of markets in the UK today is likely to be a noon announcement on the interest rate from the Bank of England monetary policy committee.
It was increased from 0.1% to 0.25% in December, and economists are predicting it will rise again to 0.5% today.
Companies reporting today
- Trading updates: BT, Compass, Cranswick, Virgin Wines UK
- AGMs: Compass, Sage Group
Other announcements
- IHS Markit/CIPS UK services PMI survey
- Bank of England interest rate decision and latest growth and inflation forecasts