A MULTINOMIAL APPROXIMATION FOR AMERICAN OPTION PRICES IN LÉVY PROCESS MODELS

This paper gives a tree-based method for pricing American options in models where the stock price follows a general exponential Lévy process. A multinomial model for approximating the stock price process, which can be viewed as generalizing the binomial model of Cox, Ross, and Rubinstein (1979) for geometric Brownian motion, is developed. Under mild conditions, it is proved that the stock price process and the prices of American-type options on the stock, calculated from the multinomial model, converge to the corresponding prices under the continuous time Lévy process model. Explicit illustrations are given for the variance gamma model and the normal inverse Gaussian process when the option is an American put, but the procedure is applicable to a much wider class of derivatives including some path-dependent options. Our approach overcomes some practical difficulties that have previously been encountered when the Lévy process has infinite activity.     

美国的城市化进程与现代城市规划联系的解读

回顾了美国城市化的独特发展历程和美国现代城市规划历史,并就二者之间的相互关系进行了探讨,以期对处于转型期的中国城市化发展有所启示和借鉴.     

美国贸易逆差:增长惯性与可持续性

美国的经常项目逆差特别是贸易逆差“历史悠久”，尤其是近年来高速增长，已引起人们广泛的关注。1990年代来的美国贸易逆差，已很难单从汇率、贸易政策及产品竞争力等单个变量来加以解释。通过运用滞后一年的时间数列回归分析及相关分析，本文得出的结论是：当期美国贸易逆差是前期美国贸易逆差的惯性增长，并且只要美国能够维持强势美元，资本与金融账户的盈余足够冲抵贸易逆差，美国的贸易逆差便具有可持续性。在本文的最后一部分，作者针对近期美国人制造的“人民币升值论”，结合近10年来中美双边贸易现实，说明美国贸易逆差与人民币汇率之间没有必然联系，人民币升值不可能改善美国的贸易收支状况。     

美国公司治理模式的变迁及启示

20世纪90年代以来美国的公司治理模式发生了重大变化，表现为：公司驻市场的作用减弱，机构投资者在公司治疗中的作用明显加强，董事会的职业化和独立化水平提高，员工开始参与企业治理，推进了产业民主化的进程，政府放松了对银行持有公司股票的限制。     

中美上市公司年度报告披露准则比较研究

本文旨在比较分析中美上市公司年度报告披露准则，为我国修订年报准则提出建议。本文首先比较分析了中美年报准则要求披露的项目内容及其特点，在此基础上，结合我／国年报披露中存在的问题，建议在修订年报准则时借鉴美国制订年报准则的经验，并提出了几点具体改进措施。     

American Parisian options

In this article, we describe the various sorts of American Parisian options and propose valuation formulae. Although there is no closed-form valuation for these products in the non-perpetual case, we have been able to reformulate their price as a function of the exercise frontier. In the perpetual case, closed-form solutions or approximations are obtained by relying on excursion theory. We derive the Laplace transform of the first instant Brownian motion reaches a positive level or, without interruption, spends a given amount of time below zero. We perform a detailed comparison of perpetual standard, barrier and Parisian options.     

Valuation of vulnerable American options with correlated credit risk

This article evaluates vulnerable American options based on the two-point Geske and Johnson method. In accordance with the Martingale approach, we provide analytical pricing formulas for European and multi-exercisable options under risk-neutral measures. Employing Richardson’s extrapolation gets the values of vulnerable American options. To demonstrate the accuracy of our proposed method, we use numerical examples to compare the values of vulnerable American options from our proposed method with the benchmark values from the least-square Monte Carlo simulation method. We also perform sensitivity analyses for vulnerable American options and show how the prices of vulnerable American options vary with the correlation between the underlying assets and the option writer’s assets.      

Bank Lending to Native American Applicants: An Investigation of Mortgage Flows and Government Guarantee Programs on Native American Lands

We investigate the efficacy of government guarantee programs for mortgage loans made on tribal lands by comparing lending outcomes for White applicants and Native Americans (NAs) living on- and off reservation lands. Simultaneous equations models with the loan-to-income ratio endogenous indicate both on- and off-reservation NA applicants experience higher conditional denial rates compared with otherwise similar White applicants. NAs living on-reservation are equally as likely to be approved for mortgage loans as off-reservation NAs. On-reservation applicants self-select lower loan-to-income ratios, and are held to a higher standard for this credit variable, likely because lower housing values and other economic variables challenge on-reservation applicants. Our findings suggest lack of financial resources, lack of applicant education about and experience with the mortgage process, low creditworthiness, and lender reluctance to confront burdensome bureaucracy limit on-reservation guarantee program success.     

美国经济会因次贷风波而衰退吗

次贷风波后弱于预期水平的美国最新经济数据加剧了市场担忧,美国经济“衰退论”大量涌现．这种极端化观点最大的弊病在于混淆了短期波动和长期趋势。结合美国经济结构特征、演化历史和最新变化,本文认为美国经济在长期内进入衰退的可能性较小,最根本的原因在于关国消费并没有出现长期萎靡的趋势,而具有易变性的投资放缓很可能是造成短期GDP增长率下降的重要因素,影响力相对较小且本身波动较大的净出口则不可能对美国长期经济增长造成较大打击。