Big 4 tech stocks erasing a total of more than $190 billion in market cap

A big reason why technology-heavy Nasdaq Composite COMP, -1.37% is dropping 1.5% in afternoon trading Thursday while the Dow Jones Industrial Average DJIA, +0.91% is rallying 292 points, or 0.9%, is the bad performance of the shares of the four biggest tech names. Of the four U.S. companies with market capitalizations of over $1 trillion, shares of Apple Inc. AAPL, -2.77% dropped 3.1%, Microsoft Corp. MSFT, -1.57% slid 1.9%, Alphabet Inc. GOOGL, -2.76% GOOG, -2.26% sank 2.9% and Amazon.com Inc. AMZN, -4.12% slid 4.1%. Based on the number of shares outstanding provided in the companies’ latest quarterly filings, the stock price declines are wiping out a total of about $191.3 billion in market capitalization. Keep in mind that the Nasdaq is a market-cap weighted index and the Dow is a price-weighted index. Of the Big 4 tech companies, only Apple and Microsoft are in the Dow. Microsoft’s stock is the 6th highest-priced Dow stock and Apple’s stock is 15th. Together, those stocks’ price drops are shaving about 60 points off the Dow’s price.