Wall Street drops as regulation worry sinks tech shares, Nasdaq falls 1.8%

US stocks dropped on Monday, with the S&P and Nasdaq suffering their worst day in just over five weeks, as concerns over increased regulation for large tech companies was spearheaded by a plunge in Facebook shares.

Facebook shares tumbled 6.8 percent as Chief Executive Mark Zuckerberg faced calls from both US and European lawmakers to explain how a consultancy that worked on President Donald Trump's election campaign gained access to data on 50 million Facebook users.

The stock had its worst day since March 2014 and was down 10.8 percent from its closing record hit on Feb. 1, to put the stock squarely in correction territory, a drop of 10 percent from its high.

Facebook's plunge weighed heavily on the S&P technology sector down 2.11 percent, as well as the Nasdaq, off more than 2 percent. Both indexes had their worst daily performance since Feb. 8.