Improving the Market Model: The 4-State Model Alternative

The present paper conducts an empirical study by examining the Market Model and the three versions of the 4-State Model (translated, rotated and un-rotated) in a mean-beta framework. Using daily returns from the CAC 40 Index's assets, we find that the explanatory power of the 4-State Model is greater than the one of the Market Model and this effect is improved by rotation. A reduction in the non-systematic risk is also observed when switching from Market Model to 4-State Models. Surprisingly, the betas are more stable when using any version of the 4- State Model. This could have a strong impact on portfolio diversification and call widely held opinion into question.Market Model, Arch

Mean-Variance-Skewness Portfolio Performance Gauging: A General Shortage Function and Dual Approach

This paper proposes a nonparametric efficiency measurement approach for the static portfolio selection problem in mean-variance-skewness space. A shortage function is defined that looks for possible increases in return and skewness and decreases in variance. Global optimality is guaranteed for the resulting optimal portfolios. We also establish a link to a proper indirect mean-variance-skewness utility function. For computational reasons, the optimal portfolios resulting from this dual approach are only locally optimal. This framework permits to differentiate between portfolio efficiency and allocative efficiency, and a convexity efficiency component related to the difference between the primal, non-convex approach and the dual, convex approach. Furthermore, in principle, information can be retrieved about the revealed risk aversion and prudence of investors. An empirical section on a small sample of assets serves as an illustration.shortage function, efficient frontier, mean-variance-skewness, portfolios, risk aversion, prudence

The role of regulatory credibility in effective bank regulation

This paper develops a model of regulated Brownian motion with an endogenous profit term to analyze the role of regulatory credibility on the stability and productivity of the banking system. We show that when regulatory intervention is perfect and costless, the volatility of the system can be substantially reduced with no loss of productivity. In fact, perfect credibility can actually reduce the volatility of intrinsically risky banking systems below the volatility of intrinsically less risky systems as banks anticipate intervention and mitigate their investment behaviour accordingly. However, when the credibility of the regime is weakened because of increased uncertainty stemming from regulation, such as random costs or imperfect timing of regulatory intervention, both the stability and productivity of the financial system are impaired. Importantly, we find that in the presence of regulatory costs and imperfect credibility, there is no universal optimal intervention policy rule. The optimal regulatory system depends on the regulator’s level of absolute risk aversion