So the US election ended with a Trump win and wild swings in the stock markets. The Dow Jones fell from 18,200 to 17,900. Then, less than a week after, stock prices rushed back up and passed 18,800. What happened? Let’s start with the simple observation that we were observing stock sales and buys by investors, who sell and buy for profit, and who have a lot of experience selling and buying. These wild movements were not a result of ignorance, and not a result of playfulness either. Investors chasing value drove prices down and back up, and lost and gained money. And, this was not a unique event, we are familiar with dramatic price changes as the market responds to uncertainty.
What drove these events was in fact a fundamental process that has been studied long, and we can go back to a paper by Hayagreeva Rao, Gerald Davis, and myself in Administrative Science Quarterly in 2001 to learn about it. People making decisions under uncertainty try to learn ways to reduce uncertainty. When they are looking for value, one way is to learn from others. After all, if we see someone moving toward one option, or away from it, their decisiveness could indicate that they know something that we don’t know. But people can be decisive for many reasons. They may have correct knowledge. They may have incorrect knowledge. They may be impatient. But learning from others can be very tricky when those others act on incorrect knowledge or impatience. This was known before our study.
What we found went one step further. Learning from others is especially tricky when those others learn from others. In that case, it is enough for some people to make decisions without correct knowledge. Others do the same learning from them, and then others do the same learning from those who learnt from them. And so on. See how this can make stock markets plunge, with very little basis in fact? Or increase? In fact, our research was based on stock market actors – not investors, but stock analysts. They want to cover firms that are good but overlooked, because analysts are most useful for investors if they give scarce information on valuable opportunities. But we found that when analysts were chasing valuable firms, they were in fact only chasing other analysts. And the later they were in learning from others, the less valuable were the firms they found.
This is a problem that extends much further than stock markets, though it is easier to prove there than elsewhere. Learning from others is a good strategy as long as it is not over-used. But, those who learn from others typically don’t stop using that strategy soon enough, so at some point it becomes costly. Again and again we see people, and firms, chasing fool’s gold: opportunities that looked good to the first who entered, but only because of incorrect information.