完全市场中的资产定价——有限离散时间情形

研究完全市场中有限离散时间情形下的资产定价问题。首先,给出了无风险收益的概念,借助无风险收益定义了一种风险中性概率。基于这个概率,得到了资产的价格等于随机现金流与随机贴现因子乘积的期望,而且资产的价格还等于资产支付关于q的期望对无风险收益的贴现值。其次,借助无风险概率考虑了资产在多期情形下的资产定价,得出了相应的股票期权公式,尤其作为推论给出了欧式看涨期权的定价公式,并对资产价格过程的鞅性作了讨论。     

A perfect storm in the financial market

This study provides a model explaining how small changes in asset prices may disrupt an entire financial market. Based on the capital asset pricing model (CAPM), our model implies that during a market crash, asset price changes affect the relative distribution of the CAPM betas of individual assets and force all tradable assets to co-move. Using US stock market data, our empirical results are consistent with the model’s predictions. Overall, the study aids understanding of the price patterns of assets during substantial market downturns, such as financial crises.     

Investor Reaction to Salient News in Closed-End Country Funds

We use panel data on prices and net asset values to test whether dramatic country-specific news affects the response of closed-end country fund prices to asset value. In a typical week, prices underreact to changes in fundamentals; the (short-run) elasticity of price with respect to asset value is significantly less than one. In weeks with news appearing on the front page of The New York Times , prices react much more; the elasticity of price with respect to asset value is closer to one. These results are consistent with the hypothesis that news events lead some investors to react more quickly.     

资产价格波动与银行系统稳定

有关金融危机的理论研究表明,资产价格波动与银行脆弱性之间存在很强的相关性。资产价格波动主要通过信贷风险渠道、市场风险渠道、经纪业务收入渠道、为附属机构注资的风险渠道及“第二回合”渠道等传导渠道影响到银行系统的稳定。发生在斯堪的纳维亚和日本的银行危机证明,资产价格剧烈波动确实会造成严重的银行问题,所以为维持银行系统的稳定,监管当局应该密切关注资产价格可能出现的剧烈下跌对银行部门可能产生的风险并采取应对方法。     

Asset pricing theory for two price economies

We show that nonlinearly discounted nonlinear martingales are related to no arbitrage in two price economies as linearly discounted martingales were related to no arbitrage in economies satisfying the law of one price. Furthermore, assuming risk acceptability requires a positive physical expectation, we demonstrate that expected rates of return on ask prices should be dominated by expected rates of return on bid prices. A preliminary investigation conducted here, supports this hypothesis. In general we observe that asset pricing theory in two price economies leads to asset pricing inequalities. A model incorporating both nonlinear discounting and nonlinear martingales is developed for the valuation of contingent claims in two price economies. Examples illustrate the interactions present between the severity of measure changes and their associated discount rates. As a consequence arbitrage free two price economies can involve unique discount curves and measure changes that are however specific to both the product being priced and the trade direction. Furthermore the developed valuation operators call into question the current practice of Debt Valuation Adjustments.     

Asset price dynamics,inflation and sectoral composition of output: a dependent economy model

This article develops a dependent economy model that focuses on the interactions between inflation and asset price dynamics under a flexible exchange rate and rational expectation. We assume that money wage adjusts instantaneously to clear the labour market. The asset prices are represented by the Tobin’s q and exchange rate. Using this framework, we will examine implications of monetary policy, fiscal policy, tariff liberalization and exogenous capital flows for inflation and asset prices, which in turn determine the allocation of labour and the sectoral composition of output. The effects of different exogenous and policy-induced shocks critically depend on the difference in the speeds of adjustment in commodity price and asset prices and multiple cross effects generated by changes in these prices.     

A Markov model for valuing asset prices in a dynamic bargaining market

This paper proposes a Markov chain model for studying the impact on asset prices of illiquidity associated with search and bargaining in an economy. The economy consists of finitely many agents who can trade only when they find each other, and any trade between agents changes the population of the agent types which affects the asset price in the future. Assuming that the equilibrium utility as well as the trade price is proportional to the asset dividend, we obtain the asset prices in steady state. Through extensive numerical experiments, we observe that the equilibrium prices exhibit the cutoff phenomenon (i.e. crash) as the fraction of pessimistic agents becomes large. Models with a market maker as well as irrational agents are also considered.     

资产价格波动与货币政策调整问题研究

近年来,尤其是在2007年,中国股票和房地产等资产价格快速增长,给宏观调控带来了很大挑战,因此央行在调整货币政策时是否应考虑资产价格的波动,已成为学术界讨论的热点问题。在这种背景下,本文通过对资产价格渠道在货币政策传导中有效性的实证检验显示,货币政策对资产价格有着较大的影响力,然而货币政策通过资产价格渠道影响实体经济效果有限。基于此,本文不主张把资产价格纳入货币政策规则,但是央行在制定货币政策时应关注资产价格的波动。     

Ambiguous Information,Portfolio Inertia,and Excess Volatility

I study the effects of risk and ambiguity (Knightian uncertainty) on optimal portfolios and equilibrium asset prices when investors receive information that is difficult to link to fundamentals. I show that the desire of investors to hedge ambiguity leads to portfolio inertia and excess volatility. Specifically, when news is surprising, investors may not react to price changes even if there are no transaction costs or other market frictions. Moreover, I show that small shocks to cash flow news, asset betas, or market risk premia may lead to drastic changes in the stock price and hence to excess volatility.     

Credit Availability and Asset Pricing Dynamics in Illiquid Markets: Evidence from Commercial Real Estate Markets

This article examines credit frictions and asset pricing in public and private markets with varying liquidity. We find that a tightening in credit availability is negatively related to subsequent price movements in private and public commercial real estate markets. Assets trading in illiquid segments of these markets are also susceptible to a feedback effect whereby changes in asset prices predict subsequent changes in credit availability. Controlling for investor demand, our findings suggest credit constraints play an economically significant asset pricing role in markets that are both highly levered and relatively illiquid.     

Recovering the probability density function of asset prices using garch as diffusion approximations

This paper uses Garch models to estimate the objective and risk-neutral density functions of financial asset prices and by comparing their shapes, recover detailed information on economic agents' attitudes toward risk. It differs from recent papers investigating analogous issues because it uses Nelson's result that Garch schemes are approximations of the kind of differential equations typically employed in finance to describe the evolution of asset prices. This feature of Garch schemes usually has been overshadowed by their well-known role as simple econometric tools providing reliable estimates of unobserved conditional variances. We show instead that the diffusion approximation property of Garch gives good results and can be extended to situations with (i) non-standard distributions for the innovations of a conditional mean equation of asset price changes and (ii) volatility concepts different from the variance. The objective PDF of the asset price is recovered from the estimation of a nonlinear Garch fitted to the historical path of the asset price. The risk-neutral PDF is extracted from cross-sections of bond option prices, after introducing a volatility risk premium function. The direct comparison of the shapes of the two PDF_s reveals the price attached by economic agents to the different states of nature. Applications are carried out with regard to the futures written on the Italian 10-year bond.     

Partial liquidation under reference-dependent preferences

We propose a multiple optimal stopping model where an investor can sell a divisible asset position at times of her choosing. Investors have $S$-shaped reference-dependent preferences, whereby utility is defined over gains and losses relative to a reference level and is concave over gains and convex over losses. For a price process following a time-homogeneous diffusion, we employ the constructive potential-theoretic solution method developed by Dayanik and Karatzas (Stoch. Process. Appl. 107:173–212, 2003). As an example, we revisit the single optimal stopping model of Kyle et al. (J. Econ. Theory 129:273–288, 2006) to allow partial liquidation. In contrast to the extant literature, we find that the investor may partially liquidate the asset at distinct price thresholds above the reference level. Under other parameter combinations, the investor sells the asset in a block, either at or above the reference level.     

The intrinsic value of gold: An exchange rate-free price index

In this paper, we propose a gold price index that enables market participants to separate the change in the ‘intrinsic’ value of gold from changes in global exchange rates. The index is a geometrically weighted average of the price of gold denominated in different currencies, with weights that are proportional to the market power of each country in the global gold market. Market power is defined as the impact that a change in a country’s exchange rate has on the price of gold expressed in other currencies. We use principal components analysis to reduce the set of global exchange rates to four currency ‘blocs’ representing the U.S. dollar, the euro, the commodity currencies and the Asian currencies, respectively. We estimate the weight of each currency bloc in the index in an error correction framework using a broad set of variables to control for the unobserved intrinsic value. We show that the resulting index is less volatile than the USD price of gold and, in contrast with the USD price of gold, has a strong negative relationship with global equities and a strong positive relationship with the VIX index, both of which underline the role of gold as a safe haven asset.     

Robust utility maximization for a diffusion market model with misspecified coefficients

The paper studies the robust maximization of utility from terminal wealth in a diffusion financial market model. The underlying model consists of a tradable risky asset whose price is described by a diffusion process with misspecified trend and volatility coefficients, and a non-tradable asset with a known parameter. The robust functional is defined in terms of a utility function. An explicit characterization of the solution is given via the solution of the Hamilton–Jacobi–Bellman–Isaacs (HJBI) equation.     

资产价格与货币政策：一个理论综述

该文对近几年国内外学术界对资产价格如何影响实体经济,货币政策是否应该考虑资产价格,如何将资产价格纳入到货币政策指标体系中等问题的研究进行了理论综述。文章认为,资产价格变动会通过财富效应,托宾Q值效应,金融加速器效应和预期效应等影响实体经济活动,但学者们对货币政策是否应该考虑资产价格以及如何将资产价格纳入到货币政策指标体系中始终存在不同看法。     

贸易顺差与资产价格:内外经济失衡传导路径的一个检验

本文对一些学者提出的内外经济失衡的关系进行了考证。结果表明外部经济的失衡虽增强了货币供给的内生性,但并不必定导致内部资产价格的高涨。因此在政策选择上,要避免面对外部经济失衡采取一些应对内部经济失衡的政策工具来调节内部经济增长过快问题。同时,出于在经济发展过程中资产价格时间序列发生结构性变化的考虑,政策制定极有必要考虑资产价格因素。     

Presidential Address: Liquidity and Price Discovery

This paper examines the implications of market microstructure for asset pricing. I argue that asset pricing ignores the central fact that asset prices evolve in markets. Markets provide liquidity and price discovery, and I argue that asset pricing models need to be recast in broader terms to incorporate the transactions costs of liquidity and the risks of price discovery. I argue that symmetric information‐based asset pricing models do not work because they assume that the underlying problems of liquidity and price discovery have been solved. I develop an asymmetric information asset pricing model that incorporates these effects.     

What Asset Prices Should Be Targeted by a Central Bank?

This paper investigates the monetary policy design for restoring equilibrium determinacy. Our interests are whether a central bank should respond to asset price fluctuations, and if so, what asset prices should be targeted. We show that a monetary policy response to the price of a productive tangible asset (capital price) is helpful for equilibrium determinacy, while that to the price of an intangible asset that reflects a firm's profit (share prices) is a source of equilibrium indeterminacy. This result comes from the two assets' prices moving in opposite directions in response to a permanent increase in inflation.     

First steps towards an equilibrium theory for Lévy financial markets

For a continuous-time financial market with a single agent, we establish equilibrium pricing formulae under the assumption that the dividends follow an exponential Lévy process. The agent is allowed to consume a lump at the terminal date; before that, only flow consumption is allowed. The agent’s utility function is assumed to be additive, defined via strictly increasing, strictly concave smooth felicity functions which are bounded below (thus, many CRRA and CARA utility functions are included). For technical reasons we require for our equilibrium existence result that only pathwise continuous trading strategies are permitted in the demand set. The resulting equilibrium asset price processes depend on the agent’s risk aversion (through the felicity functions). Even in our simple, straightforward economy, the equilibrium asset price processes will essentially only be (stochastic) exponential Lévy processes when they are already geometric Brownian motions. Our equilibrium asset pricing formulae can also be modified to obtain explicit equilibrium derivative pricing formulae.     

2010年我国货币政策取向的若干建议

继续保持适度宽松的总体基调：是2010年货币政策的基本取向：在信贷总量方面．新增信贷规模只宜做小幅度调整,控制在8万亿元左右。在信贷投放方面,更加关注优化结构,由保“量”转向保“质”;在关注重点方面,提高货币政策对资产价格变动反应的前瞻性和预见性,防范资产价格泡沫;在退出策略方面,分步实施政策调整与转向。