Facebook's security chief Stamos said to be leaving, shares under pressure

Facebook (FB) shares continued to be under pressure on Tuesday over concerns about how the company manages third-party access to users’ information.

Shares of the tech giant were down over 7% Monday afternoon,  the company’s worst daily performance in four years.

British privacy regulators are seeking a warrant to search the offices of the political consultancy Cambridge Analytica late Monday following reports that the company may have improperly gained access to data on 50 million Facebook users, according to Reuters citing a broadcast report.

The social media company said on Friday it was suspending Strategic Communication Laboratories (SCL), including their political data analytics firm, Cambridge Analytica.

According to Facebook, SCL and Cambridge Analytica improperly kept users’ data, despite telling the Silicon Valley behemoth they had destroyed them.

It was also reported, Facebook's security chief, Alex Stamos, plans to step down from the embattled social-media company this year, people familiar with the matter said, following clashes with policy executives and an internal reorganization that whittled down his responsibilities.

Facebook drew some harsh criticism from U.S. and British lawmakers over the weekend for not providing more information about how the data firm came to access the information. Meanwhile, the attorney general in Massachusetts said in social media posts Saturday that her office would launch an investigation.

Facebook added more clarity to its decision on Saturday, noting that, “the claim that this is a data breach is completely false,” reiterating that it was an issue with how the company used the information that it had accessed through the proper channels.

The major tech companies were also under pressure from a Bloomberg report claiming that the European Union is set to put a 3% tax on revenue from the big digital companies. Twitter, Amazon and Google were all lower.