It just seems logical that sticking to investing in only a small number of companies that you understand well, rather than moving down the list to your thirtieth or fiftieth favorite pick, would create a much greater potential to earn above-average investment returns.

The secret to investing is to figure out the value of something - and then pay a lot less.

The more confidence I have in each one of my stock picks, the fewer companies I need to own in my portfolio to feel comfortable.

Figure out what something is worth and pay a lot less.

The big picture is: the main thing you should be concerned about in the future are incremental returns on capital going forward. As it turns out, past history of a good return on capital is a good proxy for this but obviously not foolproof. I think this is an area where thoughtful analysis can add value to any simple ranking/screening strategy such as the magic formula. When doing in depth analysis of companies, I care very much about long term earnings power, not necessarily so much about the volatility of that earnings power but about my certainty of "normal" earnings power over time.

It just seems logical that sticking to investing in only a small number of companies that you understand well, rather than moving down the list to your thirtieth or fiftieth favorite pick, would create a much greater potential to earn above-average investment returns.

Choosing individual stocks without any idea of what you're looking for is like running through a dynamite factory with a burning match. You may live, but you're still an idiot.