SP500 last 15 minutes Friday was a technical accident. If you look at the 15 min chart here you will see the S line where the trend has turned up twice before the last 3 days. Now with 15 min to go before close it was easy to fall down through the strong S line where lots of sellers had orders. That is my take of this story. Now, it is possible that the trend will retest this breaking point and it will be interesting to see what happens then.

SP500 15 min US close