Here's what I mean...

There are two stages in stock investing.

The first is coming up with a preferred allocation among stocks, cash, bonds, etc. This stage also includes deciding how much to put in index products or exchange-traded funds (ETFs, which are a kind of mini-index) and how much active management to use.

The second stage involves the actual buy and sell decisions — when to get out, when to get in and when to go to the sidelines with safe-haven assets such as Treasury notes or gold.

What investors may not realize is the extent to which both of these decisions are now left entirely to computers. I'm not talking about automated trade matching where I'm a buyer and you're a seller and a computer matches our orders and executes the trade. That kind of trading has been around since the 1990s.