Autocorrelation

"Auto" means "self." And "correlation" is when something is related to or similar to something. So autocorrelation means you're similar to yourself...wait...what?

Let's try it another way. Autocorrelation is basically the mathematical expression of "those who do not understand the past are doomed to repeat it." But in a good way.

You're going to compare the behavior of the current returns of an investment to the returns of the investment over a previous (but similar) time period. If the current returns are positively autocorrelated to the past returns over those same time periods, your investment's behavior moving forward will probably be similar to what happened to the investment in the previous returns' time periods.

In short, if you find a stock to be highly positively-autocorrelated, and your stock showed gains in the recent past, you can probably expect the stock to show gains going forward. Probably…that's an important qualifier. Autocorrelation isn’t a guarantee. And it's also not about how much like Ford, GM is...