Nasdaq 100 futures fell 3.1%. Futures on the Dow Jones Industrial Average lost 250 points, or 0.9%.  S&P 500 futures were off by 1.4%.

Here's what traders are watching:

• Tesla dropped 15% after it failed to be added to the S&P 500 after the bell Friday.
• Facebook, Amazon, Netflix, and Alphabet were all down more than 3% in premarket trading Tuesday.
• Apple dropped 5.3%.
• Nvidia was off 6.6%.
• Zoom Video fell by 5%.
• Shares of Softbank dropped 7% on Monday.
• Shares of Disney, UPS and Ford were up in premarket trading.

Large losses in Amazon, Apple, Microsoft and Facebook drove the Composite down 3.3% leading to its worst week since March 20. Last week, the Dow fell 1.8% and the S&P 500 fell 2.3%. Even with last week's pullback, the Nasdaq is up more than 70% from its March bottom. 

"Given how extreme many of the indicators we follow had become by early this past week, we believe it will take more than just a mild decline to work off those conditions," Matt Maley, chief market strategist at Miller Tabak, said in a note on Sunday. "Therefore we still believe a correction of more than 10% is probable."

Read more here