This article investigates the dynamic and stochastic behaviour of the beta coefficient of the one-factor international capital asset pricing model (ICAPM), and its implications for the pricing of stock markets at the country level and the forecasting of stock returns in global stock markets. We apply several novel econometric techniques and conduct necessary statistical tests. We find that the ICAPM has a stochastic and dynamic beta coefficient and that the global stock market is efficient and integrated, and the world market portfolio is mean-variance efficient. We demonstrate that the dynamic and stochastic behaviour of country betas for the developed countries differs from that of developing economies. The empirical results indicate that the trend and the unexpected change of the foreign exchange rate contribute significantly to the variation patterns of country betas, and that explicit consideration of such changing characteristics will serve to increase the accuracy of stock return forecasts in global stock markets.

This article examines the dynamic and stochastic behavior of the beta coefficient (to be referred to as the currency beta) of the unbiasedness hypothesis (UH) in foreign exchange markets. We argue that the dynamics and stochastics of currency betas can be attributed to the dynamic behavior of various macroeconomic variables from different sectors of an economy, in addition to the trend variable considered in previous research. Incorporating four macroeconomic variables from the financial, real, and external sectors into the currency betas of eight currencies (developed and emerging) under a logarithmic change specification used to test the UH, we attempt to simultaneously test the behavior of currency betas in terms of nonstationarity, shifts in the mean and variance, and randomness. The vast quantity of empirical tests and results strongly suggests that the changing characteristics of currency betas are readily apparent and have important implications for the reconciliation of the controversies surrounding the legitimacy of the UH, for government exchange rate policies, and for the forecasting of future spot rates, across the developed and emerging economies under study. We also find different tales from developed and developing countries (JEL F31, F37, F47, G15).

We measure cost and profit efficiencies of banks operating in six GCC countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates) using heteroskedastic stochastic frontier (HSF) models. Our results show that measures of cost and profit efficiencies of banks vary widely across the six gulf countries over the same period.We examine whether cost and profit efficiencies of Islamic banks are significantly different from that of conventional banks. After allowing for bank risk, asset quality, environmental influences such as the level of interest rate, and country effect, we find that cost and profit efficiencies of Islamic banks are similar to that of conventional banks. Our results suggest that the country-specific variables have significant impact on cost and profit efficiencies of banks operating in GCC countries. Our findings indicate that cost and profit efficiencies of Islamic banks are more volatile than that of conventional banks.JEL Classification: G21, G28, G34, F23, F33

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