By Philip Elmer-DeWitt
January 27, 2013

FORTUNE — What happened to Apple (AAPL) in the last minute of trading Friday?

Tyler Durden, who tweets as @zerohedge, offers the Nanex chart above as evidence that it was a premeditated flash dump executed by one or more high-frequency trading algorithms. How else could 800,000 shares worth nearly $300 million be sold in 17-second intervals?

If retail investors are moving back into mutual funds, per Sunday’s
New York Times
, could it be in part because the algos have squeezed them out of what used to be their favorite stock?

For a backgrounder in how these things work I recommend Scott Patterson’s Dark Pools: High-Speed Traders, A.I. Bandits, and the Threat to the Global Financial System.

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