Traders use mental algorithms. Portfolio managers write up trading plans with expectations, theories and the actions they intend to take. Computers are programm

Traders use mental algorithms. Portfolio managers write up trading plans with expectations, theories and the actions they intend to take. Computers are programmed to execute some of those algorithms. There isn't a dividing line between what algorithms in the heads of humans are doing and what the computers are doing, except that the computers are doing it several orders of magnitude faster.