Facebook plunged to its worst loss in four years Monday and led a rout in technology companies. The social media company’s stock fell following reports that a data mining firm working for the Trump campaign improperly obtained data on 50 million Facebook users.

On Monday:

The S&P 500 index lost 39.09 points, or 1.4 percent, to 2,712.92.

The Dow Jones industrial average slid 335.60 points, or 1.3 percent, to 24,610.91.

The Nasdaq composite retreated 137.74 points, or 1.8 percent, to 7,344.24.

The Russell 2000 index of smaller-company stocks skidded 15.49 points, or 1 percent, to 1,570.56.

For the year:

The S&P 500 is up 39.31 points, or 1.5 percent.

The Dow is down 108.31 points, or 0.4 percent.

The Nasdaq is up 440.85 points, or 6.4 percent.

The Russell 2000 is up 35.05 points, or 2.3 percent.