Optimal f and Portfolio Return Optimisation in US Futures Markets

While considerable evidence has been produced concerning the efficacy of trading rules in futures markets, the results have generally not allowed for the reinvestment of profits as might be observed for real traders. Similarly, the determination of the appropriate capital allocation required per futures contract traded has been largely unstructured so making reported percentage returns questionable. This paper provides evidence of the profitability of a simple and publicly available trading rule in five futures markets but more importantly incorporates the ability to reinvest any profits via the ‘Optimal f’ technique described by Vince (1990). The results indicate that money management in speculative futures trading plays a more important role in trading rule profitability than previously considered by providing dramatic differences in profitability depending on how aggressively the trader capitalises each futures contract.Futures, Optimal f, Money Management, Trading Rules, Technical Analysis.

Liquidity management around seasoned equity offerings

We investigate firms' liquidity practices around seasoned equity offerings (SEOs). We broadly classify issuers on the basis of whether the firm belongs to an industry deemed to be financially constrained or unconstrained. We find that constrained-industry issuers tend to save more cash to conserve funding capacity in anticipating investment. Unconstrained industry issuers, in contrast, carry high debt and limited cash reflecting a sizable financial leash. We also find that the former firms experience significant cash stockpiling following new equity issues, whereasforthe lattergroup, there is a significant decline in long-term debt. In the long run, unconstrained issuers who aggressively manage liquidity pre-issue have lower operating profit. However, the relation does not hold for market-based performance because investors, observingthe liquidity information, quickly discount stock value at the time of the offering. Rather, post-issue market underperformance can be attributed to investors' downward revisions relating to the transitory nature of investment opportunities

Alterations of Blood Brain Barrier Function in Hyperammonemia: An Overview

Ammonia is a neurotoxin involved in the pathogenesis of neurological conditions associated with hyperammonemia, including hepatic encephalopathy, a condition associated with acute—(ALF) or chronic liver failure. This article reviews evidence that apart from directly affecting the metabolism and function of the central nervous system cells, ammonia influences the passage of different molecules across the blood brain barrier (BBB). A brief description is provided of the tight junctions, which couple adjacent cerebral capillary endothelial cells to each other to form the barrier. Ammonia modulates the transcellular passage of low-to medium-size molecules, by affecting their carriers located at the BBB. Ammonia induces interrelated aberrations of the transport of the large neutral amino acids and aromatic amino acids (AAA), whose influx is augmented by exchange with glutamine produced in the course of ammonia detoxification, and maybe also modulated by the extracellularly acting gamma-glutamyl moiety transferring enzyme, gamma-glutamyl-transpeptidase. Impaired AAA transport affects neurotransmission by altering intracerebral synthesis of catecholamines (serotonin and dopamine), and producing “false neurotransmitters” (octopamine and phenylethylamine). Ammonia also modulates BBB transport of the cationic amino acids: the nitric oxide precursor, arginine, and ornithine, which is an ammonia trap, and affects the transport of energy metabolites glucose and creatine. Moreover, ammonia acting either directly or in synergy with liver injury-derived inflammatory cytokines also evokes subtle increases of the transcellular passage of molecules of different size (BBB “leakage”), which appears to be responsible for the vasogenic component of cerebral edema associated with ALF

Stock price reaction to profit warnings: The role of time-varying betas

This study investigates the role of time-varying betas, event-induced variance and conditional heteroskedasticity in the estimation of abnormal returns around important news announcements. Our analysis is based on the stock price reaction to profit warnings issued by a sample of firms listed on the Hong Kong Stock Exchange. The standard event study methodology indicates the presence of price reversal patterns following both positive and negative warnings. However, incorporating time-varying betas, event-induced variance and conditional heteroskedasticity in the modelling process results in post-negative-warning price patterns that are consistent with the predictions of the efficient market hypothesis. These adjustments also cause the statistical significance of some post-positive-warning cumulative abnormal returns to disappear and their magnitude to drop to an extent that minor transaction costs would eliminate the profitability of the contrarian strategy