Centralized and decentralized control polices for a two-stage stochastic supply chain with subcontracting

An analysis of control policies for a two-stage supply chain with subcontractors at each stage is presented when decisions at each stage concerning safety stocks, backorders, and subcontracting are made jointly or in a decentralized manner. The inventory/admission control policies considered are base stock, echelon base stock and partial backordering, and the objective is to maximize the mean profit rate of the system. The optimal control parameters are found by exhaustive search using Markov chains. From numerical examples it appears that the policies which manage jointly sales and production levels in each stage provide much higher overall (system) profits than decentralized policies, although the latter are individually more profitable for the second stage. In addition, partial backordering provides the system with an extra profit above those that result from the lost sales (no backordering) and complete backordering policies. Finally, a number of numerical results show the impact of variations in certain system parameters on the optimal control parameters and the corresponding profit.     

Informed trading and liquidity in the Shanghai Stock Exchange

Dufour and Engle (J. Finance (2000) 2467) find evidence of increased presence of informed traders when the NYSE markets are most active. No such evidence, however, can be found by Manganelli (J. Financial Markets (2005) 377) for the infrequently traded stocks. This article investigates the issue of informed trading and its relation to liquidity in Shanghai Stock Exchange. Consistent with the hypothesis that information-based trade exists for all stocks, our findings suggest an increased presence of informed trading in both liquid and illiquid stocks when markets are active. Moreover, for the actively traded stocks, our results support the price formation model of Foster and Viswanathan (Rev. Financial Studies (1990) 593) that activities of informed traders deter uninformed investors from trading, thereby reducing market liquidity.     

Policy Implications of the Effects of Concentration and Multimarket Contact in China’s Airline Market

Unlike many other mergers in developed countries, which might have been assessed and their effects estimated by antitrust authorities before being granted antitrust immunity, the airline mergers that swept China’s airline industry in 2002 occurred with no antitrust challenge. These mergers provide the opportunity to study important market power issues in China’s airline markets. Given that increased concentration and multimarket contact are the main legacies of an airline merger, the effects of mergers on these variables can raise the potential for the exercise of market power. However, an examination of the period 2002–2004 during which the Chinese airline mergers occurred shows that the resulting increased concentration and enhanced multimarket contact did not have important consequences for airfares in Chinese city-pair markets. The presence of Hainan Airlines appears to have played an important role in suppressing the airfares charged by China Eastern and China Southern.     

On-Line Portfolio Selection Using Multiplicative Updates

We present an on-line investment algorithm that achieves almost the same wealth as the best constant-rebalanced portfolio determined in hindsight from the actual market outcomes. The algorithm employs a multiplicative update rule derived using a framework introduced by Kivinen and Warmuth. Our algorithm is very simple to implement and requires only constant storage and computing time per stock in each trading period. We tested the performance of our algorithm on real stock data from the New York Stock Exchange accumulated during a 22-year period. On these data, our algorithm clearly outperforms the best single stock as well as Cover's universal portfolio selection algorithm. We also present results for the situation in which the investor has access to additional "side information."     

Growth of Investor Owned and Cooperative Firms in Greek Dairy Industry

This paper examines the factors that affect the annual growth of cooperatives and investor owned firms (IOF) in Greek diary industry over the period 1990–94. A comparison based on both cooperative principals and property rights theory is made between IOFs and cooperatives to study their characteristics. However an empirical work is required to explain differences, if any, in the growth of the two types of firms within the same market. The work examines the determinants of the annual growth and it tests whether significant differences between IOFs and cooperatives exist. Ordinary least squares results show that both diversification and advertising strategies are important determinants for IOF growth, while the cooperative growth depends on capital structure and intensity and these organizations do not effectively apply competitive strategies.