Facebook: Who is investigating, and why?

Facebook’s (NASDAQ:FB) shares are falling for a second-straight session and were down more than 5% on Tuesday, adding to losses from Monday which saw stocks close down 6.8%, shaving tens of billions of dollars off of the company’s market capitalization.

The share slide came following revelations that a third-party accessed and stored data from some 50 million Facebook users. As confirmed by the social media giant, Cambridge Analytica, known for working on President Donald Trump's 2016 campaign, had improperly obtained and kept Facebook user data despite claiming it had deleted the information.

Facebook CEO Mark Zuckerberg has been silent amid the latest controversy, but he may soon have to appear in front of lawmakers.

The Federal Trade Commission (FTC) could investigate the incident, Bloomberg reported, and Facebook could receive a letter from the agency in the coming days. The FTC, responsible for enforcing companies’ privacy policies, could fine Facebook if it finds it violated a 2011 consent decree.

Separately, Fox News confirmed Facebook officials will meet with House Judiciary Committee staff as early as Wednesday to discuss the third-party data access and storage issue.

In a letter on Tuesday, the U.K. parliament requested Zuckerberg appear for a testimony to provide the company with oral evidence.

“The Committee has repeatedly asked Facebook about how companies acquire and hold on to user data from their site, and in particular about whether data had been taken without their consent,” Damian Collins, chair of the Digital, Culture, Media and Sport Committee, wrote. “Your officials' answers have consistently understated this risk, and have been misleading to the Committee. It is now time to hear from a senior Facebook executive with the sufficient authority to give an accurate account of this catastrophic failure of process.”

Zuckerberg isn’t required to testify, but the U.K. government has requested a response by March 26.

Stateside, numerous lawmakers have critiqued the situation. Sen. Amy Klobuchar, a Democrat from Minnesota, said on Twitter that Zuckerberg "needs to testify before Senate Judiciary."

Massachusetts Attorney General Maura Healey said on Twitter that "Massachusetts residents deserve answers," and announced her office will investigate.