Facebook shares plunged more than 20 percent, wiping more than $200 billion off the company's market cap and erasing $29 billion from Zuckerberg's net worth. 
Facebook reported a drop of nearly 500,000 in daily logins during the last three months of 2021. 

'People have a lot of choices for how they want to spend their time, and apps like TikTok are growing very quickly,' Zuckerberg said. He reiterated that Meta - the company that owns Facebook, Instagram and WhatsApp - is pushing hard to develop its short-form video Reels in an effort to compete with TikTok.