基于Heston's SV模型下带有违约风险的最优再保险-投资策略

对于模糊厌恶型保险公司，在可违约金融市场中，考虑其比例再保险-投资问题。假设在任意时刻保险公司可购买比例再保险和投资无风险资产、风险资产和可违约债券，其中风险资产价格服从Heston's SV (Heston's Stochastic Volatility) 模型。首先，考虑模型不确定性，采用与参考模型概率测度等价的概率测度描述替代模型。利用Girsanov变换得到保险公司在替代模型下的财富过程，并通过动态规划原理建立了相应的HJB (Hamilton-Jacob-Bellman) 方程，其中，文章用含状态依赖的不同偏好参数度量模型不确定性的模糊度。其次，分别在违约前和违约后的情况下，针对CARA (Constant Absolute Risk Aversion) 效用函数求解HJB方程，得到了最优稳键的再保险-投资策略，并给出了数值模拟和经济学解释。结果表明：相比较使用同一偏好参数的模型结果，文章的最优策略的表达式更精确，考虑的模型更符合实际金融环境。     

奈特不确定下资产定价消费模型的建立

在不确定条件下进行资产定价是金融学中的一个重要问题。受金融市场的时变性和人的参与,通常情况下很难得到如收益、利率、波动率等某些变量的精确估计值,现实金融市场中不仅存在概率意义上的不确定性,还存在模糊性,在实际投资中如何对不确定性给出正确的建模就变得非常重要。把不确定性理论引入到传统的资产定价模型中,通过引入不确定性惩罚因子和熵函数建立奈特不确定条件下的最优消费和投资组合模型,能够同时反映随机不确定性和模糊性,可满足投资者的需求。该模型是对经典模型的一种自然推广,它可以适用于不同类型的市场,不同类型的个体,有较好的适用性。     

On utility maximization under model uncertainty in discrete‐time markets

We study the problem of maximizing terminal utility for an agent facing model uncertainty, in a frictionless discrete‐time market with one safe asset and finitely many risky assets. We show that an optimal investment strategy exists if the utility function, defined either on the positive real line or on the whole real line, is bounded from above. We further find that the boundedness assumption can be dropped, provided that we impose suitable integrability conditions, related to some strengthened form of no‐arbitrage. These results are obtained in an alternative framework for model uncertainty, where all possible dynamics of the stock prices are represented by a collection of stochastic processes on the same filtered probability space, rather than by a family of probability measures.     

Dynamically consistent alpha‐maxmin expected utility

The alpha‐maxmin model is a prominent example of preferences under Knightian uncertainty as it allows to distinguish ambiguity and ambiguity attitude. These preferences are dynamically inconsistent for nontrivial versions of alpha. In this paper, we derive a recursive, dynamically consistent version of the alpha‐maxmin model. In the continuous‐time limit, the resulting dynamic utility function can be represented as a convex mixture between worst and best case, but now at the local, infinitesimal level. We study the properties of the utility function and provide an Arrow–Pratt approximation of the static and dynamic certainty equivalent. We then derive a consumption‐based capital asset pricing formula and study the implications for derivative valuation under indifference pricing.     

Estimation Uncertainty and the Equity Premium*

This paper studies a dynamic equilibrium model of asset prices in a partially observable exchange economy. It shows that the precautionary savings motive in response to estimation uncertainty can dominate the risk aversion effect, resulting in the reduction of the equity premium over short horizons. This exacerbates the equity premium puzzle. Over longer holding horizons, however, estimation uncertainty does induce higher risk premiums on equity over risk‐free coupon bonds of matching maturities, as long‐term bond yields are lowered due to the precautionary savings effect.     

A closer look at co-movements among stock returns

Correlation among financial assets is widely recognized; however, the mechanics of the relationship are not well understood. This paper investigates the microstructure of the co-movement of stock returns. The goal is to improve our understanding of correlation among stock returns by examining the conditions under which asset returns co-move on an intra-day basis. The methodology combines a traditional lead–lag model with a modified or pseudo-error correction model. Empirical evidence is presented to suggest the speed of adjustment between paired asset intra-day returns is a function of asymmetric information. Specifically, the wider an asset's spread, the faster the asset will converge to the intra-day returns of other similar assets. This result is consistent with partial adjustment model presented by Chan (Chan, K. (1993). Imperfect information and cross-autocorrelation among stock prices. The Journal of Finance:1211–1230.) which suggests market makers gain from monitoring other market makers in periods of uncertainty.     

A Jump/Diffusion Consumption-Based Capital Asset Pricing Model and the Equity Premium Puzzle

This paper derives the equilibrium excess returns on risky assets in an exchange economy where the underlying exogenous uncertainty is a combination of a pure multidimensional jump process and a diffusion model. We derive closed-form solutions for the interest rate and the risk premiums on risky assets for a traditional class of separable utility indices. Our analysis demonstrates that when the underlying jumps of the aggregate consumption process are not negligible, then the traditional form of the consumption-based capital asset princing model need not hold and the asset risk premiums may be larger than predicted by the traditional CCAPM in continuous time, based on pure Itô diffusion processes. Our analysis suggests an explanation for the large estimates of the risk premiums reported in empirical tests of the single-beta CCAPM.     

Minimum variance cross hedging under mean‐reverting spreads,stochastic convenience yields,and jumps: Application to the airline industry

Exchange traded futures contracts often are not written on the specific asset that is a source of risk to a firm. The firm may attempt to manage this risk using futures contracts written on a related asset. This cross hedge exposes the firm to a new risk, the spread between the asset underlying the futures contract and the asset that the firm wants to hedge. Using the specific case of the airline industry as motivation, we derive the minimum variance cross hedge assuming a two‐factor diffusion model for the underlying asset and a stochastic, mean‐reverting spread. The result is a time‐varying hedge ratio that can be applied to any hedging horizon. We also consider the effect of jumps in the underlying asset. We use simulations and empirical tests of crude oil, jet fuel cross hedges to demonstrate the hedging effectiveness of the model. © 2009 Wiley Periodicals, Inc. Jrl Fut Mark 29:736–756, 2009     

Governance mode for port congestion mitigation: A transaction cost perspective

Transaction cost analysis (TCA) has been applied in a wide range of academic disciplines, including economics, marketing, sociology, organization theory, and business strategy. Literature in maritime transport has had limited exposure to this versatile theoretical framework. This paper aims at developing a conceptual model that describes governance strategies that various players within the maritime sector can adopt to mitigate congestion at ports. A TCA is used to examine port congestion mitigation from a governance perspective. A theoretical analysis conducted for this paper reveals that the three characteristics of TCA – asset specificity, frequency, and uncertainty – prevail in the maritime sector, too. The first two factors, frequency, and uncertainty, contribute to port congestion, while the third factor, asset specificity, exists because to release port congestion, some players ought to make a specific investment. We use TCA to discuss the circumstances under which governance modes such as bilateral governance and vertical integration should be used to avoid congestion and other kinds of transaction costs associated with these three attributes in the maritime sector. In this study, we suggested several testable propositions to identify the mode of governance that should be selected by stakeholders to mitigate port congestion and to protect specific investments made to release congestion at ports. This line of analysis will certainly provide all the stakeholders engaged (particularly, a public policymaker) useful insight into understanding congestion from a governance perspective.     

Abandonment value and capital budgeting under uncertainty

The objective of this article is to provide a solution to the capital deepening (optimal economic life) problem encountered in capital budgeting under conditions of uncertainty. Specifically, we address the capital deepening problem where project cash flows, the terminal value of the asset, and the opportunity cost of funds are all random variables. In addition, we consider the impact of risk averse behavior on the solution to the problem, much as Sandmo has done with respect to the capital widening decision.     

ROBUST ASSET ALLOCATION WITH BENCHMARKED OBJECTIVES

In this paper, we introduce a new approach for finding robust portfolios when there is model uncertainty. It differs from the usual worst‐case approach in that a (dynamic) portfolio is evaluated not only by its performance when there is an adversarial opponent (“nature”), but also by its performance relative to a stochastic benchmark. The benchmark corresponds to the wealth of a fictitious benchmark investor who invests optimally given knowledge of the model chosen by nature, so in this regard, our objective has the flavor of min–max regret. This relative performance approach has several important properties: (i) optimal portfolios seek to perform well over the entire range of models and not just the worst case, and hence are less pessimistic than those obtained from the usual worst‐case approach; (ii) the dynamic problem reduces to a convex static optimization problem under reasonable choices of the benchmark portfolio for important classes of models including ambiguous jump‐diffusions; and (iii) this static problem is dual to a Bayesian version of a single period asset allocation problem where the prior on the unknown parameters (for the dual problem) correspond to the Lagrange multipliers in this duality relationship. This dual static problem can be interpreted as a less pessimistic alternative to the single period worst‐case Markowitz problem. More generally, this duality suggests that learning and robustness are closely related when benchmarked objectives are used.     

VALUATION OF CLAIMS ON NONTRADED ASSETS USING UTILITY MAXIMIZATION

A topical problem is how to price and hedge claims on nontraded assets. A natural approach is to use for hedging purposes another similar asset or index which is traded. To model this situation, we introduce a second nontraded log Brownian asset into the well-known Merton investment model with power law and exponential utilities. The investor has an option on units of the nontraded asset and the question is how to price and hedge this random payoff. The presence of the second Brownian motion means that we are in the situation of incomplete markets. Employing utility maximization and duality methods we obtain a series approximation to the optimal hedge and reservation price using the power utility. The problem is simpler for the exponential utility, and in this case we derive an explicit representation for the price. Price and hedging strategy are computed for some example options and the results for the utilities are compared.     

Hedging multiple price and quantity exposures

We examined the general hedging problem faced by a global portfolio manager or a pure exporting multinational firm. Most hedging models assume that these economic agents hold only a single asset in the spot market and are exposed only to a single source of price–quantity uncertainty. Such models are less relevant to many financial and exporting firms that face multiple sources of risk. In this study, we developed a general hedging model that explicitly recognizes that these hedgers are faced with multiple price and quantity uncertainties. Our model takes advantage of the full correlation structure of changes in spot prices, quantities, and forward prices. We performed simulations of the hedging model for a firm with two pairs of price and quantity exposures to demonstrate potential gains in hedging efficiency and effectiveness. © 2001 John Wiley & Sons, Inc. Jrl Fut Mark 21:145–172, 2001     

Small Firm Investment and Financing Decisions: An Option Value Approach

This paper reviews and discusses recent developments undergone by investment theory, and tries to address both financial and real decisions within an uncertain environment, here, the Italian economy. According to the recent "option value" approach to investment, if differing degrees of reversibility characterize the accumulation process by groups of firms (small and larger firms), we should expect their investment decisions to differ under uncertainty. On the other hand, asset reversibility has an influence on firm financing policy, given the observed relationship between asset and liability composition. Assuming a different degree of investment reversibility for small and larger firms, we explore how they react to interest rate uncertainty using the Italian experience during the 1980s as a benchmark. The main result of this paper is that interest rate uncertainty exerts a negative influence on firms' investment demand. The relationship is stronger for large firms than for small firms. Another result is that firm leverage also shows a negative relationship with interest rate uncertainty.     

Factors Affecting E-Mail Marketing Sourcing Decisions: A Transaction Cost Perspective

Electronic marketing strategy is an important priority for e-business, but limited research has been undertaken to understand and predict decisions regarding the insourcing or outsourcing of these marketing activities. This study focuses specifically on e-mail marketing and uses an established seven function classification of the activities which include: designing, building, testing, deploying, tracking, reporting, and analyzing. Transaction cost theory was employed as a predictor of insourcing and outsourcing decisions for each of these e-mail marketing activities. To test these functions, case studies were used for tracking the value of two attributes of transactions–asset specificity and uncertainty (behavioural uncertainty, environmental volatility, and environmental diversity)–under three levels of analysis. Results show that specific skills and tacit knowledge used to manage functions are major factors for sourcing decisions, and overpower the effect of uncertainty. It was also found that companies consider an outsourcing option for each individual function rather than the combined or whole e-mail marketing functions. The paper concludes with a discussion of limitations, implications for academics and practitioners, and future research directions.     

CONTINGENT CLAIMS VALUED AND HEDGED BY PRICING AND INVESTING IN A BASIS

Contingent claims with payoffs depending on finitely many asset prices are modeled as elements of a separable Hilbert space. Under fairly general conditions, including market completeness, it is shown that one may change measure to a reference measure under which asset prices are Gaussian and for which the family of Hermite polynomials serves as an orthonormal basis. Basis pricing synthesizes claim valuation and basis investment provides static hedging opportunities. For claims written as functions of a single asset price we infer from observed option prices the implicit prices of basis elements and use these to construct the implied equivalent martingale measure density with respect to the reference measure, which in this case is the Black-Scholes geometric Brownian motion model. Data on S & P 500 options from the Wall Street Journal are used to illustrate the calculations involved. On this illustrative data set the equivalent martingale measure deviates from the Black-Scholes model by relatively discounting the larger price movements with a compensating premia placed on the smaller movements.     

Do the magnitude and asymmetry of specific asset investments matter in the supplier–buyer relationship?

Abstract

Despite a body of literature on specific asset investments, the extant literature falls short of exploring the magnitude and symmetry of specific asset investments in supplier–buyer relationships. This paper builds on prior research to identify and examine the impact of total and asymmetric specific asset investments on commitment, trust, and conflict in supplier–buyer relationships. Covariance structure analysis is used to analyse survey data. The results show that total SAI are positively related to commitment and trust, while asymmetric SAI are negatively related to trust and positively related to conflict in supplier–buyer relationships. Decision-making uncertainty affects trust, commitment, and conflict more than any other variables. Therefore, firms should work to strengthen their relationships by increasing the magnitude of specific asset investments with the aim of increasing trust and commitment. We also discuss the limitations of this study and suggestions for future research.     

Multivariate downside risk: Normal versus Variance Gamma

Although several types of options on multiple assets are popular in today's financial markets, valuing multiasset options is still a challenge in finance. The standard framework of multivariate normality is often inappropriate, since it ignores fat tails and other stylized facts of asset returns. The variance gamma (VG) model appears to be a promising alternative. In the univariate case, it has become a standard tool in finance. The traditional way to extend the model to the multivariate case is to subordinate a Brownian motion through a univariate subordinator. In recent years, generalizations with multivariate subordinators have been proposed. Our objective is to study two versions of the multivariate VG model in a large‐scale application with multiasset options traded in an active market. Our database consists of 468 multivariate barrier reverse convertibles at the Swiss market for structured products. The Swiss market ranks among the largest in the world and is characterized by an exceptional popularity of multiple asset options. We find that there is a trade‐off between the two VG models considered: one performs better in capturing the smile, the other is more often able to capture the correlation structure. In all, based on our calibration, only 316 of 468 products can be evaluated with at least one of the two VG models. We conclude that there is a need for more flexible extensions. © 2011 Wiley Periodicals, Inc. Jrl Fut Mark     

Contingent Claims and Market Completeness in a Stochastic Volatility Model

In an incomplete market framework, contingent claims are of particular interest since they improve the market efficiency. This paper addresses the problem of market completeness when trading in contingent claims is allowed. We extend recent results by Bajeux and Rochet (1996) in a stochastic volatility model to the case where the asset price and its volatility variations are correlated. We also relate the ability of a given contingent claim to complete the market to the convexity of its price function in the current asset price. This allows us to state our results for general contingent claims by examining the convexity of their "admissible arbitrage prices."