Just a day after Facebook lost $119 billion ($176.8b) to a massive share market plunge, CEO Mark Zuckerberg he is in hot water again.

Zuckerberg and Facebook are being sued in what could be the first of many lawsuits over a disappointing earnings announcement by the social media company that wiped out billions of shareholder wealth yesterday.

The complaint filed by shareholder James Kacouris in Manhattan federal court accused Facebook, Zuckerberg and Chief Financial Officer David Wehner of making misleading statements about or failing to disclose slowing revenue growth, falling operating margins, and declines in active users.

Kacouris said the marketplace was "shocked" when "the truth" began to emerge on Wednesday from the Menlo Park, California-based company.

He said the 19 per cent plunge in Facebook shares the next day stemmed from federal securities law violations by the defendants.

The lawsuit seeks class-action status and unspecified damages.

A Facebook spokeswoman declined to comment.

Shareholders often sue companies in the US after unexpected stock price declines, especially if the loss of wealth is large.

Facebook has faced dozens of lawsuits over its handling of user data in a scandal also concerning the UK firm Cambridge Analytica. Many have been consolidated in the federal court in San Francisco.

Thursday's plunge also hit Zuckerberg's bottom-line.

Zuckerberg had been tied with Warren Buffett as the world's fourth-richest person, but the Berkshire Hathaway chairman's current US$83b fortune tops Zuckerberg's US$66b, Forbes magazine said.

Buffett now ranks third among the world's billionaires, while Zuckerberg is sixth.

Facebook shares fell another 0.8 per cent on Friday, closing at US$174.89 on the Nasdaq.

Intel previously held that record with a US$91b one-day collapse back in September 2000.

Founder Mark Zuckerberg, who has a 13 per cent stake in Facebook, saw his fortune dropped by more than US$12b in less than 24 hours, to around US$74b.

The fall came after the social media giant revealed three million European users had closed their accounts since the Cambridge Analytica data scandal. The record decline pushed the tech-heavy Nasdaq more than one per cent lower.