Investor Sentiment in News and the Calendar Anomaly -- New Evidence from a Large Textual Data

The well-known stock market adage "sell in May and go away" arose from long-term stock market seasonality in major financial markets around the globe. Kamastra, Kramer and Levy (2003) present evidence that Seasonal Affective Disorder causes this seasonality, as this condition has a profound effect on people’s mood and makes people increasingly risk averse as daylight diminishes with the onset of winter. In this paper, we present evidence that change in market mood is reflected in the prospect statement in the news text. We employ a text-mining technique to analyze a large quantity of newspaper articles for the period 1986–2010 and created our market mood proxy. We find investor psychology is skewed to optimism in the first half of the calendar year and pessimism in the latter. We also find that semi-annual mood fluctuation is synchronous with market seasonality.