This book directly focuses on finding optimal trading strategies in the real world and supports that with a well-defined theoretical foundation that allows trading strategy problems to be solved. Critically, it also delivers a menu of actual solutions that can be applied by traders with various risk profiles and objectives in markets that exhibit substantial tail risk. It shows how the Markowitz approach leads to excessive risk taking, and trader underperformance, in the real world. It summarizes the key features of Utility Theory, the deficiencies of the Sharpe Ratio as a statistic, and develops an optimal decision theory with fully developed examples for both 'Normal' and leptokurtotic distributions.

This dissertation analyzes trading behavior in financial markets from multiple perspectives. In chapter 1, "Exploratory Trading," I investigate the mechanisms underlying high-frequency traders' capacity to profitably anticipate price movements. I develop a model of how a trader could gather valuable private information by using her own orders in an exploratory manner to learn about market conditions. The model's predictions are borne out empirically, and I find that this "exploratory trading" model helps to resolve several central open questions about high-frequency trading. Chapters 2 and 3 focus on the trading behavior of individuals. Chapter 2, "Foundations of the Disposition Effect: Experimental Evidence," (co-authored with Johanna Mollerstrom), presents and analyzes results from a laboratory experiment intended to examine if and how "regret aversion"--aversion to admitting mistakes--affects people's trading decisions. Although the experimental results resolve little about regret aversion specifically, they reveal some novel and unexpected effects, most importantly that subjects radically changed their trading decisions when they were compelled to devote a minimal amount of extra attention. In chapter 3, "Price Targets," I analyze how rational investors who privately observe information of indeterminate quality use prices to learn about whether or not their private information is valuable. I derive implications about trading behavior that not only help to explain a variety of empirical puzzles, but also generate several new testable predictions. Although these three essays differ considerably in methodology and focus, they all address the same basic issue of understanding the foundations of trading behavior.

The first part of the thesis consists of three chapters focusing on herd behavior in financial markets. Chapter one reviews the herding literature while chapter two studies a market where informed and noise traders show up sequentially and anonymously in front of a competitive and risk neutral market maker. Traders can in some cases observe whether some of their predecessors were informed, although they cannot observe their private in- formation. This creates an informational asymmetry between the traders and the market maker which generates herd behavior. I find that herd and contrarian behavior is gener- ated more easily in better-informed markets than in poorly informed ones. Informational cascades can never occur and the market learns in the limit. Moreover, I illustrate how a market dominated by herding features a price that is more informative of the asset value than the price of a market where traders always follow their signal. I also discuss how contrarianism has the exact opposite effect by decreasing price informativeness. In chap- ter two I consider the case of multiple trading rooms, where traders can in some cases observe whether some of the predecessors coming from the same room were informed. I first analyze herding conditions for the case of disconnected rooms where agents trading during the same time exhibit information correlation, and find that herding is more likely to occur in a market with positive correlation than in a market without correlation. I then link rooms by means of a network structure which dictates which rooms' predecessors one can observe. I check whether it is possible for a trader to herd with traders outside his own neighborhood instead of with his direct neighbors. I find that the answer to this question is negative and that herding cannot spread from one part of the market to another. Finally, I bring together information correlation and the network structure and I illustrate the example of a market where there are trading histories such that herd behavior can lead to the complete loss of information and, once herding has started, learning can be recovered only if noise traders enter the market. In the second part of the thesis I build a signalling model of delegated portfolio management where the manager can be of different qualities which affect the performance of the closed-end fund under his management. I find that in his effort to appear of high quality, the manager sends signals to the market which affect the share price of the fund in such a way that momentum and reversal are generated. While in the momentum phase, the price accumulates a discount with respect to its net asset value; during the reversal phase, the discount narrows and the price reverses back towards the net asset value of the fund.

The virtues and failings of market economies are at present widely debated and the outcome of the debate is of practical importance. This book contains essays that address these issues of economic policy ranging from privatisation of industry and financial markets to education and the proposal for an internal market in the health service. Apart from two theoretical pieces, particular markets, and proposals for creating such markets, are studied. The contributors are distinguished specialists in their field of economics and their analysis offers important lessons for social and political philosophy and will generate considerable interest.