Optimal Portfolio Construction using Sharpe’s Single-Index Model: Evidence from Chittagong Stock Exchange

Abstract

The study aims to apply Sharpe’s single-index model of portfolio construction and evaluate the model’s performance on the securities traded on Chittagong Stock Exchange (CSE). For this purpose, the last seven years' daily closing price data of 122 sample securities as well as the daily closing index value of the benchmark market index, CASPI, has been utilized. Sharpe’s model smoothens the intricate process of portfolio construction by suggesting a unique number, called the cutoff rate, to measure the desirability of each security’s inclusion in the final portfolio. In this study, 38 securities qualified to be a part of the final portfolio, hence, the optimal investment weight for each of them is calculated. An industry-wise analysis reveals that four industries account for about 68 percent of the final portfolio weight. The constructed portfolio yields a daily mean return of 0.1095 percent, which is equivalent to about 49 percent in effective annual terms. The overall portfolio risk, indicated by standard deviation, is found to be only 0.6425 percent. The portfolio beta of 0.3496 also indicates that there is significant nonexistence of systematic risk. An evaluation of the portfolio parameters explicitly reveals that it has outperformed every sample security as well as the market index, in offering the best risk-return combinations, by a large margin. Therefore, the study found Sharpe’s model of portfolio construction highly effective in optimizing risk and return in the context of CSE.