One small tweak to an algorithm, one giant crater in Mark Zuckerberg's net worth. The Facebook CEO took a $3 billion hit to his net worth on Friday as his company's stock dipped following news of major changes to the company's News Feed. Facebook warned that the changes, meant to boost the visibility of posts by friends and family, could mean people spending less time on Facebook. That would mean less ads, which means less money. Facebook stock declined about 4 percent.