Bubbles and Investment Horizons∗

The current theoretical literature makes contradicting predictions regarding the impact of an investor’s horizon on his optimal trading strategy in the presence of bubbles. We analyze this relation empirically using a Regime Switching Model to identify bubbles and crashes. We base our analysis on industry returns and find high positive returns after bubbles at the one-month horizon. At intermediate horizons of 2-4 months our findings are mixed, but thereafter, for horizons up to five years, returns following a bubble are again more positive than returns in the absence of a bubble. We compare a mean-variance as well as a downside-risk averse investor’s portfolio allocation in the presence and absence of a bubble. The weight allocated to the bubbly asset is higher for horizons up to 5 years. These findings suggest that even for a rather unsophisticated trader who does not follow daily market news, riding bubbles is a more profitable strategy than refraining from investing in the bubbly asset. Given the broad range of horizons during which riding bubbles is the optimal strategy, our results question the idea that bubbles are zero-sum games