Facebook shares fell 5 percent Tuesday on reports that CEO Mark Zuckerberg agreed to\u00a0testify in front of Congress\u00a0about the company\u2019s data scandal.\r\nThe crisis began on March 16 after Facebook said it was suspending data analysis company Cambridge Analytica for allegedly harvesting data from more than 50 million Facebook users. Cambridge Analytica worked on Donald Trump\u2019s presidential campaign.\r\nSince then, Facebook\u2019s stock has plunged 18 percent, wiping out nearly $80 billion from the social networking giant\u2019s market value in the process.\r\nZuckerberg\u2019s net worth has fallen by about $14 billion (he is still worth $61 billion, though).\r\nTech stocks in general have taken a hit since the Facebook allegations first came to light. The Nasdaq is down 6 percent.\r\nAnd other social media companies, most notably YouTube owner Google and Twitter, have both nosedived as well.\r\nShares of Google parent Alphabet fell 7 percent since March 16, while Twitter has plunged 20 percent.\r\nTwitter was down 12 percent on Tuesday after noted short seller Citron Research has changed its tune on the company\u2019s stock.\r\nInvestors worry that Facebook, Google and Twitter could face tougher regulations in the United States and around the world because of the Cambridge Analytica controversy.\r\nIf that happens, it could stymie growth for all three companies \u2014 but Facebook in particular.\r\nInvestors also worry that users might flee these companies because of privacy concerns. And if users flee, advertisers may eventually jump ship too.\r\nThat\u2019s why several Wall Street analysts have lowered their price targets and earnings estimates for Facebook during the past week and a half.\r\nBut others have boosted their forecasts, arguing that the worst will soon pass and that investors are overreacting.\r\nIt\u2019s impossible to know if it\u2019s the Facebook bulls or bears who will ultimately be proven correct. But it\u2019s clear that confidence in Facebook and other once-hot tech companies has been shaken.\r\n\u201cWhile the scandal is likely to blow over, investors should be aware that a continued sell-off in this sector would not be surprising, and if another scandal were to hit, it just might break the tech sector\u2019s back,\u201d said Craig Birk, executive vice president of portfolio management at investing firm Personal Capital in a note Tuesday.