Big media-based technology stocks Amazon, Google, Netflix, and Facebook sank faster than the market overall, with Amazon down 6.3% to $1,538, Netflix losing 5% to $284.97, Google sinking 4.8% to $1,02 and Facebook dropping, 2.3% to $142.09.
Snap was down 4.6% to $5.99, while Twitter was virtually unchanged -- up 0.1% to $32.39.
Analysts point to fears of a global economy slowdown, as well as the effects of U.S. tariffs.
Among broader market indices, Dow Jones Industrials was down 1% to 24,439, Nasdaq was down 1.6% to 7050 and the S&P 500 lost 0.7% to 2,641.
At one point, Dow Jones was down more than 560 points. Earlier in the day, it was up more than 350 points -- a 900-point swing.
All this occurred while big traditional media companies were virtually unchanged or higher: Discovery rose 0.8% to $30.36, while CBS inched up 0.6% more to $54.13; AMC Networks added 0.6% to $54.38; 21st Century Fox was up 0.6% more to $45.41; and Walt Disney slipped 0.1% to $113.04.
Viacom was up 1.6% to $30.46 and Sinclair Broadcast Group rose 1.5% to $26.77.
Major cable companies and mobile/broadband communications businesses posted some of the better gains: Comcast Corp. added 2.1% to $35.99; Verizon Communications was up 1.8% to $56.48; AT&T grew 1.9% to $29.64; and Charter Communications was up 2% more to $300.85.