https://techcrunch.com/2018/07/26/facebook-officially-loses-123-billion-in-value/

In what could be the biggest one-day drop of all time, Facebook shares opened at $174.89, down 19.6 percent compared to yesterday’s closing price of $217.50 (NASDAQ:FB).

When it comes to market capitalization, Facebook was worth $629.6 billion yesterday. The company is now worth $506.2. In other words, Facebook has lost $123.4 billion in value overnight.