Portfolio optimization under dynamic risk constraints: Continuous vs. discrete time trading

We consider an investor facing a classical portfolio problem of optimal investment in a log-Brownian stock and a fixed-interest bond, but constrained to choose portfolio and consumption strategies that reduce a dynamic shortfall risk measure. For continuous- and discrete-time financial markets we investigate the loss in expected utility of intermediate consumption and terminal wealth caused by imposing a dynamic risk constraint. We derive the dynamic programming equations for the resulting stochastic optimal control problems and solve them numerically. Our numerical results indicate that the loss of portfolio performance is not too large while the risk is notably reduced. We then investigate time discretization effects and find that the loss of portfolio performance resulting from imposing a risk constraint is typically bigger than the loss resulting from infrequent trading.

Testing Weak Form of Market Efficiency in Nepal

The paper investigates the weak form of market efficiency for overall and sectorial indices. The Nepalese stock returns are found not being normally distributed during the study period. The autocorrelation of the stock returns was reduced by correcting the data with the application of the methodology suggested by Miller et al. (1994). The Nepalese stock market has suffered from the problem of thin-trading. Overall, the Nepalese market is not weak-form efficient on the basis of the analysis performed by employing observed returns series; but it is found a weak-form efficient in case of the analysis while using corrected data after adjusting infrequent trading. Hence, the study is supported to the random-walk and weak form of market efficiency.

Insider Trading in Hong Kong: Tests of Stock Returns and Trading Frequency

The main purpose of this paper is to examine the legal insider trading activities by directors of companies listed on the Hong Kong Exchange over the period 1993 to 1999. One characteristic of insider trading in Hong Kong is the high frequency of transactions and the large amounts of money involved. Inside purchases appear to signal and correct undervaluation and inside sales appear to signal and correct overvaluation. In contrast to research from Britain and the United States, insider sales are more informative than purchases. On average, insiders earn HK$91,297 per trade, while outsiders who mimic insiders' transactions earn minimal returns. Many firms suffer from infrequent trading and our results are consistent with directors engaging in inside transactions so as to help create a market for the shares. In additional tests, we find that the frequency of insider trading is a function of information asymmetry.

Intraday Price Change and Trading Volume in the KTB Futures and Futures Option Markets

This study examines the impacts of the KTB futures options, newly introduced at the Korea Futures Exchange (KOFEX) on May, 2002, on the intraday volatility and liquidity of the KTB futures markets for the period from January 17, 2002, to August 30, 2002. The results show that the volatility of the KTB futures appears to have increased since the inception of the KTB futures options. However, the increase in volatility largely disappears after controlling for the effects of volume, time-to-maturity, day-of-the-week, and bid-ask bounce. There is some mixed evidence regarding the impact on the liquidity of the KTB futures markets, in the sense that the trading volume has increased significantly whereas the bid-ask spreads have widened too. The KTB futures price changes are more likely to lead the price changes of the KTB futures options by about 15 minutes, which is probably due to the infrequent trading problem on the part of the KTB futures options. Finally, though infrequently traded, the put-futures parity condition is rarely violated, and thus is difficult to be exploited for arbitrage transactions, indicating that the two markets are closely linked each other.