Testing CAPM using Markov switching model: the case of coal firms

In this study, the relation between the coal firms that are traded in New York Stock Exchange and S&P500 index is analyzed. The return of the coal firms and the market return are analyzed by using traditional CAPM and two-state Markov regime switching CAPM (MS-CAPM). According to the Likelihood Ratio test, two-state regime MS-CAPM gives better results and indicates a non-linear relation between return and risk. It is found that beta shows variability in regard to low and high volatile periods making linear CAPM to provide deviated results.