After a six-hours long massive outage in Facebook system, the social media giant lost nearly $6 billion.

As reported by Bloomberg, Facebook stocks were down nearly 5% on Monday, and 15% down compared to mid-September. As expected, these numbers also affected Zuckerberg’s worth, which ended the day at $121.6 billion.

Users began experiencing issues with Facebook’s services (which includes WhatsApp and Instagram) around 8:40 AM PT.

While the exact reasons that caused the outage remain unclear, it seems that Facebook was affected by a DNS problem that “wiped” the paths to Facebook domains. Even the company’s internal network was affected, which made the outage even longer and more complicated.

By 6PM ET, both Facebook, Instagram, and WhatsApp were back online. 

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