The Nasdaq closed 0.6% lower at 10,853.55. At its session high, the composite rose as much as 1%; it was down more than 1.7% at one point as well.
Apple dropped 1.3% and Amazon fell by 1.9%. Facebook, Alphabet and Microsoft were all down.
The S&P 500 eked out a small gain after gyrating between solid gains and steep losses. The broader-market index closed about 0.1% higher at 3,340.97.
Meanwhile, the Dow Jones Industrial Average ended the day up 131.06 points, or 0.5%, at 27,665.64. The 30-stock average was up 294.24 points, or 1.1%, at its session high and fell as much as 86.46 points.
All three of the major averages posted steep losses for the week. The Nasdaq fell 4.1% week to date for its biggest weekly decline since March. The S&P 500 had its worst one-week performance since June, falling 2.5%. The Dow fell 1.7% this week.
