March 26 (Reuters) - Shares of Facebook Inc fell more than 5 percent on Monday after the U.S. Federal Trade Commission made public its investigation of the social network following the disclosure that data of 50 million users got into the hands of political consultancy Cambridge Analytica.
The move by the U.S. consumer protection regulator adds to pressure from lawmakers in the United States and Europe for Facebook Chief Executive Mark Zuckerberg to explain how his company handles user data.
The FTC rarely confirms an investigation publicly before it files a complaint except in cases of significant public interest.
Facebook also faces rising discontent from advertisers and users. U.S. auto parts retailer Pep Boys on Monday suspended all advertising on Facebook, joining internet company Mozilla Corp which made a similar move last week.
Opinion polls published on Sunday in the United States and Germany cast doubt over the trust people have in Facebook as the firm ran advertisements in British and U.S. newspapers apologizing to users.
Fewer than half of Americans trust Facebook to obey U.S. privacy laws, according to a Reuters/Ipsos poll released on Sunday, while a survey published by Bild am Sonntag, Germanys largest-selling Sunday paper, found 60 percent of Germans fear that Facebook and other social networks are having a negative impact on democracy.
(Editing by Bill Rigby)