The Effects of Investor Behavior on Market Predictability

Abstract

This study aimed to test the effects of investor behavior on the predictability of the market by testing CAPM estimation errors in negative growth period and growth period of the market. This study also aims to draw attention to the existence of some factors that may affect the CAPM estimation errors. Negative growth period is the period in which irrational behavior is likely to occur. Growth period is the period when irrational behaviors are less common. CAPM estimation errors calculated by jensen’s alpha, sharpe ratio, sortino ratio and treynor ratio were compared by T-Test and Mann-Whitney U Test during negative growth periods and growth periods.

USA-S&P 500, Germany-DAX 100, England-FTSE 100, France-CAC All Tradable, Canada-S&P TSX, Japan-Nikkei 225 developed countries and their indices and India S&P BSE 200, China-SSE Composite, South Africa &-FTSE JSE African All Share, Turkey-BIST 100 developing countries and their indices included in the study. Between January 31,2005 and December 31,2018 monthly closing prices of the indices, monthly closing prices of stocks listed in consumer staples sectors and consumer discretionary sectors were used.

As a result of the study, it has been observed that CAPM estimation errors calculated by jensen’s alpha and treynor ratio in consumer staples and consumer discretionary sectors in developed and developing countries do not differ during negative growth periods and growth periods of the market. It cannot be said that CAPM is more reliable or unreliable in negative growth periods compared to growth periods. It has been determined that CAPM estimation errors calculated by sharpe ratio and sortino ratio differ during negative growth periods and growth periods. It can be said that CAPM is less reliable in negative growth periods compared to growth periods.