This paper explores the effects of innovation efficiency on technology gap and product diversity between a leading firm and its competitor. Our analysis shows some interesting results: when innovation efficiency is sufficiently large and increases, the leading firm may expand technology gap, and...

This paper derives a new method for comparing the weak-form efficiency of markets. The author derives the formula of the Sharpe ratio from the ARMA-GARCH model and finds that the Sharpe ratio just depends on the coefficients of the AR and MA terms and is not affected by the GARCH process. For...