Signal vs Noise

Ptolemy, Galileo, and Financial Markets

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Assume nothing, new models and analytical tools, coupled with constant revision, questioning everything, reassessing, and re-analyzing, are essential to success in today’s markets. Often, and we are seeing that in today’s market, relying on bad assumptions, dogma, or prior belief can be disastrous.

This story about medieval astronomy applies directly to investment strategies, market valuations, and portfolio construction today. It’s the same lesson –begin by questioning the very assumptions on which an entire system is built. There is also a very specific application of this model that is particularly current.

One of the most valuable lessons is to assume no knowledge and analyze closely every initial assumption. Nothing is so obvious that it can’t be questioned. Unexamined ideas and assumptions will eventually be useless. Any assumptions and any model used to explain and predict anything (whether it’s the movement of planets or financial markets) needs to go back to first principles and discard any assumptions, preconceived knowledge, or bias.

Animal spirits and the madness of markets

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When to sell is more important than what to buy. One of the biggest mistakes investors make is thinking that their purchase decision is the most important decision they will make. This is misguided because most losses are lost opportunities. They may be buying decisions that were never made, but most likely, they are selling decisions where the decision to sell was made too soon. When Warren Buffett owned 5% of Disney in the 1960s, he made a 50% return. He happily sold the stock. But investment decisions should not be made based on historical returns. Once again, all investments are predictions for the future. Regardless of whether the investment you currently hold has generated a great return or lost you money, what will it do from this point on?

Buying or selling is a crucial investment decision because you are always either buying or selling. There is no such thing as “holding.” If you own something you have bought it. If you would not buy it today but continue to own it simply because you bought it in the past, and not making an investment decision, just simply being inactive. If you are an investor who is buying or selling. Selling decisions tend to be inefficient. One does not need to be active, but one does need to think like an owner. If you own a great company, there is little reason to do anything else other than stay on top of developments within that company and industry to make sure they can remain a great company. Eventually, they will revert to the mean. More than anything, that is an investor’s job – figure out when the company will revert to the mean. That means they will either be losses or tremendous gains in the future as this trend occurs.

Nothing stays above average.