The macroeconomic role of currency reserve accumulation in emerging markets—The Asian experience

The impact of currency reserve accumulation is controversially discussed since reserve accumulation potentially destabilises the international financial system and causes crises due to higher systemic risk. The main aim of this paper is to put the macroeconomic role of currency reserve accumulation for four Asian economies under closer scrutiny. The key question is whether accumulating currency reserves is beneficial from a long‐run perspective. Based on a vector error correction approach, we start by analysing long‐run steady‐state relationships between currency reserves, exchange rates against the US dollar, real GDP and interest rates. Our findings show that cumulated currency reserve shocks significantly affect real GDP . A likely explanation for our finding is that accumulation of reserves has supported growth through providing liquidity and supporting the development of the financial sector for the economies under observation.     

Pricing Defaultable Bonds Using a Lévy Jump‐Diffusion Model

This paper uses a reduced‐form approach to derive a closed‐form pricing formula for defaultable bonds. The authors specify the default hazard rate as an affine function of multiple variables which follow the Lévy jump‐diffusion processes. Because such specification allows greater flexibility in the generation of a valid probability of default, their pricing model should be more accurate than the valuation models in traditional studies, which ignore the jump effects. This paper also proposes a new method for estimating the parameters in a Lévy Jump‐diffusion process. The real data from the Taiwanese bond market are used to illustrate how their model can be applied in practical situations. The authors compare the pricing results for the influential variables with no jump effects, with jump magnitudes following the normal distribution, and with jump magnitudes following the gamma distribution. The results reveal that the predictive ability is the best for the model with the jump components. The valuation model shown in this paper should help portfolio managers more accurately price defaultable bonds and more effectively hedge their portfolio holdings.     

Optimal reserve management and sovereign debt

Most models currently used to determine optimal foreign reserve holdings take the level of international debt as given. However, given the sovereign's willingness-to-pay incentive problems, reserve accumulation may reduce sustainable debt levels. In addition, assuming constant debt levels does not allow addressing one of the puzzles behind using reserves as a means to avoid the negative effects of crisis: why do not sovereign countries reduce their sovereign debt instead? To study the joint decision of holding sovereign debt and reserves, we construct a stochastic dynamic equilibrium model calibrated to a sample of emerging markets. We obtain that the reserve accumulation does not play a quantitatively important role in this model. In fact, we find the optimal policy is not to hold reserves at all. This finding is robust to considering interest rate shocks, sudden stops, contingent reserves and reserve dependent output costs.     

OPTIMAL CONSUMPTION AND INVESTMENT FOR A LARGE INVESTOR: AN INTENSITY‐BASED CONTROL FRAMEWORK

We introduce a new stochastic control framework where in addition to controlling the local coefficients of a jump‐diffusion process, it is also possible to control the intensity of switching from one state of the environment to the other. Building upon this framework, we develop a large investor model for optimal consumption and investment that generalizes the regime‐switching approach of Bäuerle and Rieder (2004) .     

全球外汇储备激增及管理策略的国际比较

自1995年以来,全球尤其是新兴经济国家外汇储备表现出了史无前例的特征:规模急剧增加、国家集中度提高、地区分布特征明显等。外汇储备激增和外汇储备的过量会给国内宏观经济带来一系列的风险和成本,增加了官方外汇储备资产管理的难度。本文对外汇储备激增国际背景下全球主要储备国或地区外汇储备管理的经验做了比较分析,并对我国的外汇储备管理提出了建议。     

中国超额外汇储备的社会成本

依据持有1美元储备资产的社会成本等于私人部门从国外借入短期债务的成本和中央银行从其流动性资产中所获得的收益之间的差额的方法,采用EMBI利差数据计算了中国持有超额外汇储备的社会成本,约为GDP的1.5%。本文认为增加流动性的最优战略是增加储备与减少短期外债并用。     

Financial versus Monetary Mercantilism: Long‐run View of Large International Reserves Hoarding

The sizeable hoarding of international reserves by several East Asian countries has been frequently attributed to a modern version of monetary mercantilism – hoarding international reserves in order to improve competitiveness. From a long‐run perspective, manufacturing exporters in East Asia adopted ‘financial’ mercantilism – subsidising the cost of capital – during decades of high growth. They switched to hoarding large international reserves when growth faltered, making it harder to disentangle the monetary mercantilism from the precautionary response to the heritage of past financial mercantilism. Monetary mercantilism also lowers the cost of hoarding, but may be associated with negative externalities leading to competitive hoarding. From this viewpoint, this paper makes three observations on the East Asian reserve accumulation. First, the recent large hoarding of reserves in Japan and Korea occurred in the aftermath of the growth strategy that combined export promotion and credit subsidisation (financial mercantilism). Second, whether the ultimate motive is mercantilist or precautionary, the ongoing reserve hoarding in Asia contains an element of competitive hoarding, which is likely to have negative externalities among countries involved. Finally, China's hoarding of reserves partly reflects the precaution against the financial fragility that is likely to follow the slowing of economic growth.     

The pricing of foreign currency options under jump‐diffusion processes

In this article, the authors derive explicit formulas for European foreign exchange (FX) call and put option values when the exchange rate dynamics are governed by jump‐diffusion processes. The authors use a simple general equilibrium international asset pricing model with continuous trading and frictionless international capital markets. The domestic and foreign price level are introduced as state variables that contain jumps caused by monetary shocks and catastrophic events such as 9/11 or Hurricane Katrina. The domestic and foreign interest rates are stochastic and endogenously determined in the model and are shown to be critically affected by the jump risk of the foreign exchange. The model shows that the behavior of FX options is affected through the impact of state variables and parameters on the nominal interest rates. The model contrasts with those of M. Garman and S. Kohlhagen (1983) and O. Grabbe (1983), whose models have exogenously determined interest rates. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:669–695, 2007     

ROBUST UTILITY MAXIMIZATION WITH LÉVY PROCESSES

We study a robust portfolio optimization problem under model uncertainty for an investor with logarithmic or power utility. The uncertainty is specified by a set of possible Lévy triplets, that is, possible instantaneous drift, volatility, and jump characteristics of the price process. We show that an optimal investment strategy exists and compute it in semi‐closed form. Moreover, we provide a saddle point analysis describing a worst‐case model.     

Asymmetric covariance in spot‐futures markets

This article studies how the spot‐futures conditional covariance matrix responds to positive and negative innovations. The main results of the article are achieved by obtaining the Volatility Impulse Response Function (VIRF) for asymmetric multivariate GARCH structures, extending Lin (1997) findings for symmetric GARCH models. This theoretical result is general and can be applied to analyze covariance dynamics in any financial system. After testing how multivariate GARCH models clean up volatility asymmetries, the Asymmetric VIRF is computed for the Spanish stock index IBEX‐35 and its futures contract. The empirical results indicate that the spot‐futures variance system is more sensitive to negative than positive shocks, and that spot volatility shocks have much more impact on futures volatility than vice versa. Additionally, evidence is obtained showing that optimal hedge ratios are insensitive to the well‐known asymmetric volatility behavior in stock markets. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:1019–1046, 2003     

我国外汇储备影响因素的实证研究及其对策

近几年来，我国外汇储备过度增长，过多的外汇储备带来了资源的浪费和持有外汇机会成本的增加，因此引起了国内很多专家学者对此问题的关注。本文利用协整的回归方法对影响我国外汇储备的主要因素进行了实证检验，实证结果表明：外债、汇率、GDP、FDI对外汇储备具有长期的协整均衡关系，而进口倾向对外汇储备的影响不显著；短期误差修正模型中GDP和进口倾向影响不显著。本文根据影响外汇储备的长短期因素对我国外汇储备的管理提出了政策性建议。     

Just‐in‐Time Retail Distribution: A Systems Perspective on Cross‐Docking

Cross‐docking is a just‐in‐time strategy for distribution logistics. It is aimed at reducing inventory levels and distribution lead times by creating a seamless flow of products from suppliers to customers. Prior supply chain literature has argued that creating such a seamless product flows requires a holistic view on cross‐docking management, aimed at synchronizing cross‐docking operations at the distribution center with its inbound and outbound network logistics. This paper provides an in‐depth case study illustrating how cross‐docking operations can be managed more holistically in a retail distribution context. A discrete event simulation model has been developed to understand and improve the cross‐docking operations of a large grocery retailer in the Netherlands. The model is used to quantitatively evaluate two proposed changes that exploit opportunities in the design and control of the retailer's distribution network. An extensive real‐world data set is used as input to the model. Overall, the case and simulation results show that a holistic cross‐docking management approach can indeed improve system‐wide performance, which further stresses the importance of making cross‐dock operational decisions making and network decisions together.     

Sharing the value‐at‐risk under distributional ambiguity

This paper considers the problem of risk sharing, where a coalition of homogeneous agents, each bearing a random cost, aggregates their costs, and shares the value‐at‐risk of such a risky position. Due to limited distributional information in practice, the joint distribution of agents' random costs is difficult to acquire. The coalition, being aware of the distributional ambiguity, thus evaluates the worst‐case value‐at‐risk within a commonly agreed ambiguity set of the possible joint distributions. Through the lens of cooperative game theory, we show that this coalitional worst‐case value‐at‐risk is subadditive for the popular ambiguity sets in the distributionally robust optimization literature that are based on (i) convex moments or (ii) Wasserstein distance to some reference distributions. In addition, we propose easy‐to‐compute core allocation schemes to share the worst‐case value‐at‐risk. Our results can be readily extended to sharing the worst‐case conditional value‐at‐risk under distributional ambiguity.     

HIGH‐ORDER SHORT‐TIME EXPANSIONS FOR ATM OPTION PRICES OF EXPONENTIAL LÉVY MODELS

The short‐time asymptotic behavior of option prices for a variety of models with jumps has received much attention in recent years. In this work, a novel second‐order approximation for at‐the‐money (ATM) option prices is derived for a large class of exponential Lévy models with or without Brownian component. The results hereafter shed new light on the connection between both the volatility of the continuous component and the jump parameters and the behavior of ATM option prices near expiration. In the presence of a Brownian component, the second‐order term, in time‐t, is of the form , with d₂ only depending on Y, the degree of jump activity, on σ, the volatility of the continuous component, and on an additional parameter controlling the intensity of the “small” jumps (regardless of their signs). This extends the well‐known result that the leading first‐order term is . In contrast, under a pure‐jump model, the dependence on Y and on the separate intensities of negative and positive small jumps are already reflected in the leading term, which is of the form . The second‐order term is shown to be of the form and, therefore, its order of decay turns out to be independent of Y. The asymptotic behavior of the corresponding Black–Scholes implied volatilities is also addressed. Our method of proof is based on an integral representation of the option price involving the tail probability of the log‐return process under the share measure and a suitable change of probability measure under which the pure‐jump component of the log‐return process becomes a Y‐stable process. Our approach is sufficiently general to cover a wide class of Lévy processes, which satisfy the latter property and whose Lévy density can be closely approximated by a stable density near the origin. Our numerical results show that the first‐order term typically exhibits rather poor performance and that the second‐order term can significantly improve the approximation's accuracy, particularly in the absence of a Brownian component.     

A NEW LOOK AT SHORT‐TERM IMPLIED VOLATILITY IN ASSET PRICE MODELS WITH JUMPS

We analyze the behavior of the implied volatility smile for options close to expiry in the exponential Lévy class of asset price models with jumps. We introduce a new renormalization of the strike variable with the property that the implied volatility converges to a nonconstant limiting shape, which is a function of both the diffusion component of the process and the jump activity (Blumenthal–Getoor) index of the jump component. Our limiting implied volatility formula relates the jump activity of the underlying asset price process to the short‐end of the implied volatility surface and sheds new light on the difference between finite and infinite variation jumps from the viewpoint of option prices: in the latter, the wings of the limiting smile are determined by the jump activity indices of the positive and negative jumps, whereas in the former, the wings have a constant model‐independent slope. This result gives a theoretical justification for the preference of the infinite variation Lévy models over the finite variation ones in the calibration based on short‐maturity option prices.     

A contango‐constrained model for storable commodity prices

This article presents a model of commodity price dynamics under the risk‐neutral measure where the spot price switches between two distinct stochastic processes depending on whether or not inventory is being held. Specifically, the drift of the spot price is equal to the cost of carry when the stock is positive. Conversely, whenever the drift of the spot price is less than the cost of carry, no inventory is being held. The properties of the spot price and the forward curves implied by this model are illustrated and analyzed with the use of numerical examples. A comparison with the single‐factor model by E. S. Schwartz (1997) is also provided. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:1025–1044, 2005     

TIME‐CHANGED MARKOV PROCESSES IN UNIFIED CREDIT‐EQUITY MODELING

This paper develops a novel class of hybrid credit‐equity models with state‐dependent jumps, local‐stochastic volatility, and default intensity based on time changes of Markov processes with killing. We model the defaultable stock price process as a time‐changed Markov diffusion process with state‐dependent local volatility and killing rate (default intensity). When the time change is a Lévy subordinator, the stock price process exhibits jumps with state‐dependent Lévy measure. When the time change is a time integral of an activity rate process, the stock price process has local‐stochastic volatility and default intensity. When the time change process is a Lévy subordinator in turn time changed with a time integral of an activity rate process, the stock price process has state‐dependent jumps, local‐stochastic volatility, and default intensity. We develop two analytical approaches to the pricing of credit and equity derivatives in this class of models. The two approaches are based on the Laplace transform inversion and the spectral expansion approach, respectively. If the resolvent (the Laplace transform of the transition semigroup) of the Markov process and the Laplace transform of the time change are both available in closed form, the expectation operator of the time‐changed process is expressed in closed form as a single integral in the complex plane. If the payoff is square integrable, the complex integral is further reduced to a spectral expansion. To illustrate our general framework, we time change the jump‐to‐default extended constant elasticity of variance model of Carr and Linetsky (2006) and obtain a rich class of analytically tractable models with jumps, local‐stochastic volatility, and default intensity. These models can be used to jointly price equity and credit derivatives.     

A SUPPLY CHAIN‐ORIENTED APPROACH OF WORKING CAPITAL MANAGEMENT

This article analyzes and illustrates the role of payment terms for working capital improvements in supply chains. So far, research has shown how individual industries and powerful companies were able to enhance their cash‐to‐cash cycles at both their supplier's and customer's expense. From a “network perspective,” the exploitation of individual advantages by a single powerful company lowers the overall financial wealth of the supply chain. Therefore, a collaborative working capital management approach is proposed, by which the cash‐to‐cash cycles of companies with the lowest weighted average cost of capital (WACC) should be extended, while companies with higher financing costs are relieved by a shortened cash‐to‐cash cycle. An unequal distribution of power, however, between supply chain members can be the main hindrance for developing a collaborative working capital management solution.     

中国外汇储备增长对CPI指数影响的滞后期研究

本文对我国1995年第一季度至2011年第三季度的外汇储备数据与中国消费者物价指数(consumerpriceindex,以下简称CPI)的相关性进行研究,通过实证检验分析外汇储备和CPI的影响期,结果表明外汇储备的增长与CPI存在长期关系。短期来看,上一期的CPI指数和上一期的外汇储备数额对当期的CPI有影响。通过Granger检验发现外汇储备的增长对CPI影响的滞后期为2年。     

Cognitive Lock‐In Effects on Consumer Purchase Intentions in the Context of B2C Web Sites

The perspective of power law of practice and human capital model asserts that cognitive search costs, cognitive transaction costs, and cognitive switching costs are three lock‐in mechanisms that a business‐to‐consumer (B2C) Web site holds to retain customers. Whether the ability of customer value or the lock‐in mechanism is more dominant for retaining online shoppers has received recent attention, but remains unresolved in the literature. This study sheds light on perceived value and cognitive lock‐in to develop a research model to predict consumer purchase intentions. Empirical results obtained from a survey of customers of a B2C Web site are used to examine the proposed model. Implications of cognitive lock‐in and product cues for increasing purchase intentions are also discussed.