When you look at selling behavior in financial markets, the most robust empirical fact is familiar: people sell winners too quickly and hang on to losers too long. Traditional explanations lean heavily on prospect theory — loss aversion, an S-shaped value function, and so on. But a recent paper by Brettschneider, Bruno and Henderson prods […]

Markets are supposed to respond to information. New facts arrive, prices adjust, some bald man on CNBC opines and we all move on. But that tidy story assumes something big: that investors are always paying attention. Anyone who works with other people (or really just lives in the world) knows that in reality, attention is […]

When people talk about bubbles, the story is usually psychological. Investors get euphoric, abandon discipline, extrapolate recent returns, and eventually panic. This narrative goes back at least to Kindleberger’s Manias, Panics, and Crashes and remains the default explanation in both the media and policy circles. Even Eugene Fama, in his Nobel lecture, framed bubbles as […]

Since 1950 the average daily return on the S&P 500 has been about 0.0368% which annualizes to just about 8% a year And that is a good reward for doing nothing. But we have written several times, that a disproportionate amount of the S&P return is realized around holidays. Christmas gives another example of this […]

One of the enduring myths in finance is that markets are ruthlessly efficient, powered by sober institutions running disciplined processes. The reality, as the paper “The Morning After: Late-night TV and the Stock Market” by Cheema et al (available on SSRN), is that sometimes the only thing moving the S&P 500 is Stranger Things dropping […]