NEW YORK, Aug. 24 -- Costco rose. So did Alphabet, Amazon, Booking Holdings, Mondelez and Microsoft. Of the thirty-two largest Nasdaq companies Eastern Herald checked shortly after 12:35pm in New York, fifteen were higher on the day and the middle stock in the sample was down just 0.13 per cent.

The Nasdaq 100 was down 0.64 per cent.

That gap is the entire session. An index falling five times as fast as its median constituent is not describing a market in retreat. It is describing a market where a small number of very large positions are being sold hard enough to drag everything else with them, and on Monday those positions were semiconductors and memory.

Nasdaq Today: The Indices, and What They Disagree About

The composite fell 0.34 ...