The effect of US individual investor sentiment on industry‐specific stock returns and volatility

This paper examines the effect of rational and irrational investor sentiment on the stock return and volatility of US auto, finance, food, oil and utility industries.

The American Association of Individual Investors Index (AAII) is used as a proxy for US individual investor sentiment. The US market fundamentals are regressed on investor sentiment in order to capture the effect of macroeconomic risk factors on investor sentiment. Then impulse response functions (IRFs) are generated from a VAR model to investigate the effect of unanticipated movements in US investor sentiment on both industry‐specific stock return and volatility.

The results show a significant impact of investor sentiment on stock return and volatility in all the industries. We find that the positive rational component of US individual investor sentiment tends to increase the stock return in these industries. We also document that unanticipated increase in the rational component of US individual investor sentiment has a significant negative impact only on the industry volatilities of US auto and finance industries.

The results are based only on the 1999 – 2010 US industry‐specific stock return and volatility data and are confined to these industries.

The findings of this paper can help investors to improve their asset return generating models by incorporating investor sentiment. The findings can also help policymakers to design policies that stabilize sentiment and reduce volatility and uncertainty in the stock markets.

This paper adds to the growing literature on behavioral finance by filling a gap and addressing the impact of investor sentiment in the various US industries.