Hubby Explains The Wall Street WTF Just Happened

This morning, I ask hubby, who watches CNBC all day --"Not all day," he corrects me -- to explain in simple terms the Wall Street Plunge from Hell.  Here's his response: "Apparently, and I'm no expert, it looks like a large negative trade was made by mistake, billions instead of millions, which triggered (long pause here) sophisticated computer algorithms (duh!) to protect the down side from huge loses.  (I've stopped listening at this point.)  The New York Stock Exchange slowed its trading down by design and the trading computers bypassed that exchange and went to other exchanges to execute the stop-losses... #$%@, what's it called?  Stop limits.  So there was a downward spiral as everyone was rushing to protect their positions.  P&G went from the mid-60s to the high-30s in about a minute, which is not a normal trading range by any measure.  (At this point, I've gone to the market, walked the dog, repainted the house and started a load of laundry.)  Basically, the machines took over and caused the problem."  Well.  Thanks for clearing that up, honey.