This study examines the stability of the CAPM before and after the recent global financial crisis in the Johannesburg Securities Exchange (JSE). Firms’ betas are derived from OLS and M-estimation regressions. Fixed and random effects are employed to estimate the linear and the nonlinear version of the CAPM. Evidence against a stable beta emerges after the crisis but not before. The latter holds for the non-linear paradigm as well.
Keywords : Panel data; CAPM; South Africa; Global financial crisis.