Vector-valued coherent risk measures

We define (d,n)-coherent risk measures as set-valued maps from into satisfying some axioms. We show that this definition is a convenient extension of the real-valued risk measures introduced by Artzner et al. [2]. We then discuss the aggregation issue, i.e., the passage from valued random portfolio to valued measure of risk. Necessary and sufficient conditions of coherent aggregation are provided.Received: February 2004, Mathematics Subject Classification (2000): 91B30, 46E30JEL Classification: D81, G31     

Asymptotic analysis for optimal investment and consumption with transaction costs

We consider an agent who invests in a stock and a money market and consumes in order to maximize the utility of consumption over an infinite planning horizon in the presence of a proportional transaction cost . The utility function is of the form U(c) = c^1-p/(1-p) for p > 0, . We provide a heuristic and a rigorous derivation of the asymptotic expansion of the value function in powers of , and we also obtain asymptotic results on the boundary of the no-trade region.Received: July 2003, Mathematics Subject Classification (1991): 90A09, 60H30, 60G44JEL Classification: G13Work supported by the National Science Foundation under grants DMS-0103814 and DMS-0139911.     

Pricing derivatives of American and game type in incomplete markets

In this paper the neutral valuation approach is applied to American and game options in incomplete markets. Neutral prices occur if investors are utility maximizers and if derivative supply and demand are balanced. Game contingent claims are derivative contracts that can be terminated by both counterparties at any time before expiration. They generalize American options where this right is limited to the buyer of the claim. It turns out that as in the complete case, the price process of American and game contingent claims corresponds to a Snell envelope or to the value of a Dynkin game, respectively.On the technical level, an important role is played by -sub- and -supermartingales. We characterize these processes in terms of semimartingale characteristics.Received: June 2003, Mathematics Subject Classification (2000):   91B24, 60G48, 91B16, 91A15, 60G40JEL Classification:   G13, D52, C73The authors want to thank PD Dr. Martin Beibel for the idea leading to the proof of Proposition A.4 and both anonymous referees for many valuable comments. The second author gratefully acknowledges financial support by the Deutsche Forschungsgemeinschaft through the Graduiertenkolleg Angewandte Algorithmische Mathematik at Munich University of Technology and by the Fonds zur Förderung der wissenschaftlichen Forschung at Vienna University of Technology.     

No arbitrage and closure results for trading cones with transaction costs

In this paper, we consider trading with proportional transaction costs as in Schachermayer’s paper (Schachermayer in Math. Finance 14:19–48, 2004). We give a necessary and sufficient condition for , the cone of claims attainable from zero endowment, to be closed. Then we show how to define a revised set of trading prices in such a way that, firstly, the corresponding cone of claims attainable for zero endowment, , does obey the fundamental theorem of asset pricing and, secondly, if is arbitrage-free then it is the closure of . We then conclude by showing how to represent claims.      

Satisfying convex risk limits by trading

A random variable, representing the final position of a trading strategy, is deemed acceptable if under each of a variety of probability measures its expectation dominates a floor associated with the measure. The set of random variables representing pre-final positions from which it is possible to trade to final acceptability is characterized. In particular, the set of initial capitals from which one can trade to final acceptability is shown to be a closed half-line . Methods for computing are provided, and the application of these ideas to derivative security pricing is developed.Received: May 2004, Mathematics Subject Classification (2000): 91B30, 60H30, 60G44JEL Classification: G10Steven E. Shreve: Work supported by the National Science Foundation under grants DMS-0103814 and DMS-0139911.Reha Tütüncü: Work supported by National Science Foundation under grants CCR-9875559 and DMS-0139911.     

On irregular functionals of SDEs and the Euler scheme

We prove a sharp upper bound for the error $\mathbb {E}|g(X)-g(\hat{X})|^{p}We prove a sharp upper bound for the error in terms of moments of , where X and are random variables and the function g is a function of bounded variation. We apply the results to the approximation of a solution to a stochastic differential equation at time T by the Euler scheme, and show that the approximation of the payoff of the binary option has asymptotically sharp strong convergence rate 1/2. This has consequences for multilevel Monte Carlo methods. The author was supported by the Finnish Graduate School in Stochastics and Statistics, the Ellen and Artturi Nyyss?nen Foundation, and the Academy of Finland, project #110599.     

Efficient estimation of drift parameters in stochastic volatility models

We study the parametric problem of estimating the drift coefficient in a stochastic volatility model , where Y is a log price process and V the volatility process. Assuming that one can recover the volatility, precisely enough, from the observation of the price process, we construct an efficient estimator for the drift parameter of the diffusion V. As an application we present the efficient estimation based on the discrete sampling with δ _n →0 and n δ _n →∞. We show that our setup is general enough to cover the case of ‘microstructure noise’ for the price process as well.      

Robust utility maximization for complete and incomplete market models

We investigate the problem of maximizing the robust utility functional . We give the dual characterization for its solution for both a complete and an incomplete market model. To this end, we introduce the new notion of reverse f-projections and use techniques developed for f-divergences. This is a suitable tool to reduce the robust problem to the classical problem of utility maximization under a certain measure: the reverse f-projection. Furthermore, we give the dual characterization for a closely related problem, the minimization of expenditures given a minimum level of expected utility in a robust setting and for an incomplete market.Received: September 2004, Mathematics Subject Classification (2000): 62C20, 62O05, 91B16, 91B28JEL Classification: D81, G11I thank Hans Föllmer for his help when writing this paper. Furthermore, I thank Alexander Schied for discussing the topic with me and Michael Kupper and the referees for their helpful remarks.     

On a Simple Econometric Approach for Utility-Based Asset Pricing Model

The Journal of Finance has published an important paper entitled A Simple Econometric Approach for Utility-Based Asset Pricing Model by Brown and Gibbon (1985). The main purpose of this paper is to extend the research of Brown and Gibbons (1985) and Karson, Cheng and Lee (1995) in estimating the relative risk aversion (RRA) parameter in utility-based asset pricing model. First, we review the distributions of RRA parameter estimate . Then, a new method to the distribution of is derived, and a Bayesian approach for the inference of is proposed. Finally, empirical results are presented by using market rate of return and riskless rate data during the period December 1925 through December 2001.     

On the Validity of the Wiener Process Assumption in Option Pricing Models: Contradictory Evidence from Taiwan

This study tests the validity of the critical assumption underlying the option pricing model that the log form of the stock price movements follows the Wiener process, i.e., stock price movements follow a geometric Brownian motion. Using data compiled from the Taiwan Stock Exchange (TSE), this study's major empirical findings are as follows: first, the null hypothesis that the log of the stock prices is normally distributed is rejected; second, the null hypothesis that the stock price in log form has mean [ln P _s + (µ- ²)_t] and variance t is rejected; third, the null hypothesis that successive non-overlapping increments of the log of the stock price are independent from each other is also rejected. These empirical findings undermine the validity of the Wiener process assumption which is fundamental to many option pricing models.     

Weighted V@R and its Properties

The paper deals with the study of a coherent risk measure, which we call Weighted V@R. It is a risk measure of the form where μ is a probability measure on [0,1] and TV@R stands for Tail V@R. After investigating some basic properties of this risk measure, we apply the obtained results to the financial problems of pricing, optimization, and capital allocation. It turns out that, under some regularity conditions on μ, Weighted V@R possesses some nice properties that are not shared by Tail V@R. To put it briefly, Weighted V@R is “smoother” than Tail V@R. This allows one to say that Weighted V@R is one of the most important classes (or maybe the most important class) of coherent risk measures.     

Estimating the term structures of corporate debt

This paper investigates the corporate bond market by estimating monthly interest rate term structures for investment grade credit classes using both S&P's and Moody's ratings. Term structures are modeled by a piecewise constant forward rate curve and estimated on noncallable coupon paying bonds issued by industrial firms. The iterative estimation algorithm minimizes the sum of squared errors between market prices and model prices while identifying and removing outliers from the sample. Although the forward rate model is successful at pricing corporate debt, additional factors are found to be significant at explaining the residual price error that remains after the forward rate model is fit to market prices. Six necessary no-arbitrage conditions are derived for the term structures of risky and risk-free debt. Occasionally, some of these no-arbitrage conditions are violated and a few violations are asymptotically statistically significant. Finally, trading strategies that capture mispricing in the corporate debt market and violations of no-arbitrage bounds are discussed.This paper was adapted from my dissertation, completed at Cornell University. An earlier version of this paper was titled The Term Structures of Corporate Debt. Thanks to participants at the Cornell University finance workshop, Warren Bailey, Peter Carr, Antoine Giannetti, and especially Robert Jarrow for their helpful comments.     

Edokko Options: A New Framework of Barrier Options

In this paper, we will give a new framework of barrier options to generalize`Parisian Option' and `Delayed Barrier Option'. Take a stopping time asthe caution time. When occurs, derivatives are given `Caution'. After, if K.O. time =() occurs, derivative contractsvanish. We simply say that first `Caution' second `K.O.'. Using thisframework, designs of barrier options become more flexible than before and newrisk management will be possible. New barrier options in this category arecalled Edokko Options or Tokyo Options.     

The Role of Analysts’ Forecasts in Accounting-Based Valuation: A Critical Evaluation

This paper critically evaluates the use of analysts forecasts in accounting-based valuation. Specifically, I assess the usefulness and the limitation of analysts forecasts in predicting future earnings and in explaining the market-to-book ratio, in light of a comprehensive set of 22 explicit information items, including: economic rent proxies, conservative accounting proxies, earnings quality signals, transitory earnings proxies, industry characteristics, and risk and growth proxies. While analysts forecasts capture 45–83% of the information from these sources depending on model specifications, they do not appear to fully incorporate certain information items. In particular, proxies for conservative accounting and transitory earnings are incrementally useful in predicting future earnings; proxies for economic rents, conservative accounting, and risk are incrementally useful in explaining the market-to-book ratio. Collectively, these results validate the use of analysts forecasts as a parsimonious proxy for forward-looking information in accounting-based valuation and suggest how to improve on their use.JEL Classification: D4, G12, M4     

Bid-ask bounce and speads in the foreign exchange futures market

This paper examines the intraday bid-ask bounce in Deutschemark and Japanese yen futures prices. The intraday Markovian bid-ask bounce process, which leads to a desirable equilibrium condition of reaching a bid or an ask transaction type with equal chances, is identified. A second-order Markov chain transition matrix model is used to derive a generalized estimator of bid-ask spreads in the foreign exchange futures market. It incorporates the conditional probabilities of a subsequent transaction being the same type as the current transaction's () and that of the next transaction being the same as the current type but different from the previous type (). The specification is {-Cov(P _t ,P _t+1 )/[(1–)(–)]}^1/2. The empirical results show that the average implied bid-ask spread is about $10, which is less than one tick's value of $12.50. It is also found that spreads are higher at the beginning and end of the trading day than the rest of the day, reflecting the uncertainty due to information flows and overnight inventory carrying costs, respectively.     

“Investor sentiment” and the closed-end fund puzzle: A 7 percent solution

Lee, Shleifer, and Thaler (1991) argue that the irrational noise trader model of DeLong, Shleifer, Summers, and Waldmann (1990) ... is consistent with the published evidence on closed-end fund prices. ... However, Lee, Shleifer, and Thaler provide no indication of how much of the variability of a closed-end fund's discounts and premiums is due to such investor sentiment. Using the signal extraction technique of French and Roll (1986) to measure noise, this article estimates that on average only 7 percent of the variance of a standardized measure of weekly changes in discounts and premiums can be attributed to noise-trading activity. Investor sentiment, therefore, seems to account for very little of a closed-end fund's discount and premium variability over time.     

Optimal Consumption Taxes and Social Security Under Tax Measurement Problems and Uncertainty

A representative individual lives for two periods; works when young and depends on savings and a government operated social security system when old—the returns on both sources of income, when old, are random. Due to administrative problems the returns to savings are observed with some measurement error. Two alternative consumption tax systems are considered; the Registered Asset Treatment (RAT) and the Non-Registered Asset Treatment (NRAT). The advantage of the RAT is that it can perform a social insurance role while the disadvantage is that it imposes measurement error risk. Correlation between the random return on saving and its measurement error can provide a risk-hedging role that can be further strengthened by the RAT version. The NRAT version neither provides social insurance nor imposes measurement error risk. Both tax systems hedge against the uncertainties in the social security system. The taxpayer engages in precautionary saving in response to future uncertainty.     

Nonparametric prediction for the time-dependent volatility of the security price

In this paper we consider a continuous time model for the security price with the time-dependent volatility. It is shown that the non-normality and non-linear dependency of the short-term return, the major characteristics observed on many financial assets, can be incorporated into our model. In order to evaluate the option price formula on the model we propose a nonparametric predictor for the volatility function without reference to a specific functional form. We examine the so-called continuous record asymptotics and show that the proposed predictor is asymptotically minimax for a wide class of the volatility functions. One of the most important results is that the application of the Black-Scholes method can be justified by plugging the proposed predictor in the standard Black-Scholes formula even if the volatility changes over time.