The central part of the reason is that due to so many stocks to be covered daily (all over the world) computers are the backbone of the buy/sell in all stocks every where. The modelsused to regulate this also require human confirmations periodically, and in specific hot stocks, constantly.

This has almost become a "Self Fulfilling Prophicy", but for the necessary human confirmation part, from time to time, and frequently to constantly for HOT Stocks.

It's in the theory built into the Models.

Old Joe

PS: Calling it a day!