GATT,Preferential/Regional Trading Blocs and Agricultural Trade*

Agricultural trade impasses have again frustrated the GATT process. Interest in preferential/regional trading blocs is increasing. the paper probes the theoretical and empirical consequences of preferential arrangements instead of multilateral liberalization. It concludes that in a second-best world preferential arrangements could either improve or decrease global welfare. For agricultural trade, previous experience suggests that in regional groupings such as the EC trade diversion exceeded trade creation. This results from trade distorting domestic policies. Prospects for liberalization of agricultural trade under either GATT or preferential arrangements are limited. the consequences for small agricultural exporters are not positive.     

A MULTINOMIAL APPROXIMATION FOR AMERICAN OPTION PRICES IN LÉVY PROCESS MODELS

This paper gives a tree-based method for pricing American options in models where the stock price follows a general exponential Lévy process. A multinomial model for approximating the stock price process, which can be viewed as generalizing the binomial model of Cox, Ross, and Rubinstein (1979) for geometric Brownian motion, is developed. Under mild conditions, it is proved that the stock price process and the prices of American-type options on the stock, calculated from the multinomial model, converge to the corresponding prices under the continuous time Lévy process model. Explicit illustrations are given for the variance gamma model and the normal inverse Gaussian process when the option is an American put, but the procedure is applicable to a much wider class of derivatives including some path-dependent options. Our approach overcomes some practical difficulties that have previously been encountered when the Lévy process has infinite activity.     

The Impact of Option Introduction on Stock Return Variances: The Role of Bid-Ask Spreads, Return Autocorrelations, and Intrinsic Variances

The purpose of this paper is to examine changes in stock return variances following option introduction. The sample consists of National Market System stocks and employs both transaction returns and returns based on bid and ask quotes. Variances are decomposed into portions attributable to bid-ask spreads, return autocorrelations, and intrinsic variances. Spreads play a negligible role in explaining variance changes. A generally positive component to short-term autocorrelations falls following option introduction, increasing variances over short holding periods. Intrinsic variances fall prior to the October 1987 crash, but do not change after the crash with option introduction.     

Competitive and Information Effects of Cross-Border Stock Listings

We examine the effect of 269 cross‐border listings on rivals in the listing and domestic markets and find that U.S. rivals experience significant gains whereas domestic rivals do not. Both competitive and information effects are important in explaining the reaction of U.S. rivals. Regarding the competitive effects, the reaction of rivals is less favorable when listings originate in developed countries and more favorable when listing firms do not have prior operating presence in the United States. Regarding the information effects, the reaction is less favorable when listings are combined with equity offerings and more favorable when the listing is the first to occur within an industry.     

Accidents will happen: safety-critical knowledge and automated control systems

This article presents findings from a study of control operators that raise concerns about safety-critical knowledge, culture and training. It is argued that the adoption of automated control systems can hinder the transfer of knowledge amongst operators, and this becomes an increasingly serious hazard as tacit knowledge is lost because of employee turnover.