, Columnist
It Takes an Epidemic to Show Markets Are Efficient
The Wuhan virus just provided a natural experiment in financial theory that medical researchers could only dream of.
A random walk through Wuhan.
Photographer: HECTOR RETAMAL/AFP/Getty Images
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Making sense of the last few days in markets requires some of the skills of a doctor. The patient has some severe symptoms, some of which can plainly be attributed to a disease. But is some other medical condition also at work? It can be difficult to tell, particularly as doctors, like those who work in capital markets, don’t have the ability to perform a controlled experiment. But we need to try.