The size of last Thursday’s loss by Facebook could be overstated—but not easily. The company lost 19 percent of its market capitalization, dropping from $630 billion to $510 billion. It was the largest single-day loss for a U.S.-listed company at any time. Smaller losses continued on Friday and Monday.

What triggered the massive sell-off—the company’s report of slow revenue growth and slowest-ever user growth during the second quarter—hardly explains it. Facebook’s other high-profile problems clearly contributed to the loss: the inability of the main Facebook app to generate ad revenue, new and stringent regulations on data protection imposed by the European Union, the use of the platform by Russian-linked accounts to spread disinformation, the improper sale of personal data to third parties, and the company’s struggle to monitor accounts for racist filth and other forms of depravity. But these problems have been known for months, and in any case the company’s other apps, Instagram and WhatsApp, go from strength to strength.