The Dow sank 527 points Thursday — its worst day in weeks — after UnitedHealth reported a disappointing quarter and slashed its full-year forecast, sending shares tumbling over 20% and dragging the larger index lower.

Nvidia dropped 6.9% after it said the U.S. government is restricting exports of its H20 chips to China, citing worries that they could be used to build a supercomputer. The restrictions could mean a hit of $5.

Nvidia is caught in the middle of an escalating trade war between the world’s two largest economies. Nvidia on Tuesday said it will take a $5.5 billion financial hit after Washington placed fresh restrictions on the export of its H20 artificial intelligence chips to China,