I try my best at Aleph Blog to phrase things in a way that conveys my level level of certainty. ?But I have my doubts. ?Learning to live or deal with doubts is a hallmark of a good investor.

So as the stock price drops, drops, and drops again, what do I do? ?I reread the fundamental data to see what I might have missed. ?I read contrary opinions. ?Then I ask the question: knowing what you know now, would this qualify to be in the portfolio? ?If not, I sell it. ?In rare cases, if I think it is unfairly trashed, I will make it a double-weight. ?So far, I have not lost on anything I made a double-weight.

All investing involves doubt. ?We don’t know the future; we are making educated guesses at best. ?Am I sure about future earnings? ?No. ?Do I know what industries will outperform? ?No. ?In general I have done well with both, but it is an art, not a science.

I like my methods, partly because they are designed to live in a world of uncertainty. ? Why do I diversify? ?Uncertainty. ?Why do I do rebalancing trades? ?Uncertainty. ?Why do I limit my ability to trade, except at mid-quarter? ?Uncertainty. ?Why do I focus on value and use of free cash flow? Uncertainty.

I could go on and give the same answer: “Uncertainty.” ?My methods attempt to thrive in uncertainty by choosing factors and companies that seem to be able to do well given uncertainty.

I don’t always win, but my wins have exceeded my losses versus the market over the last 13 years. ?Does that mean I will do as well over the next 13 years? ?No. ?I mean, I hope I do as well, ?but there is no guarantee. ?The math on investor performance is such that Bill Gross and Warren Buffett could be random flukes. ?I don’t think they were lucky — I think they were skilled. ?But the statistics won’t prove it.

I also have my doubts about the US economy. ?Is it growing? ?Is the labor market healthy? ?I don’t know. ?Short-term data is volatile. ?Wise investors will wait and see, unless they have a differential insight that most others do not have.

I lean toward the idea that things are weak,but I don’t know that for sure. ?Thus I seek for contrary data.

This is the life of the investor who has ideas, but knows they might be wrong. ? What will happen to my overweight in Energy? ?Am I overexposed in Tech and Insurance?

In the end, doubts are a part of investing. ?You can’t avoid them, despite hard work in analysis, because you can never know what you missed.

That said, when my doubts grow, and the price has not fallen in tandem, I sell. ?My quarterly purge of a few companies lets me express my doubts, but in a reasoned way, not merely responding to a fall in the stock price.

Therefore, be reasoned in your decisions in stock investing, and always be forward-looking, because you can’t change the past.