我国城市绿地系统可持续发展的障碍性因素及对策

本文分析了当前制约我国城市绿地系统建设的社会、经济和生态环境因素,提出了采取加强政府宏观调控和依靠科技进步、建立技术支持系统等对策,实现城市市绿地系统的可持续发展。     

Optimal static quadratic hedging

We propose a flexible framework for hedging a contingent claim by holding static positions in vanilla European calls, puts, bonds and forwards. A model-free expression is derived for the optimal static hedging strategy that minimizes the expected squared hedging error subject to a cost constraint. The optimal hedge involves computing a number of expectations that reflect the dependence among the contingent claim and the hedging assets. We provide a general method for approximating these expectations analytically in a general Markov diffusion market. To illustrate the versatility of our approach, we present several numerical examples, including hedging path-dependent options and options written on a correlated asset.     

The role of asset payouts in the estimation of default barriers

In the barrier option model of corporate security valuation, the firm’s creditors impose a default-triggering barrier on the firm value to protect their claim. Two disputed issues in the literature are whether the implied default barrier is positive, and whether it is above or below the book value of the firm’s liabilities. We extend the model of Brockman and Turtle (2003) by embedding asset payouts in the valuation of shareholders’ equity. Using a sample of US stocks from the NYSE, AMEX, and NASDAQ exchanges, our paper exploits market and firm information to compute the implied default barrier for thirty 2-digit SIC groups, including industrials and banks. Our results show that the implied default barrier is lower than it is in the received literature, and it can be less than total liabilities, even zero for some firms. The implied physical default probabilities are significantly lower in the presence of payouts, providing a closer fit to the historical corporate default rates, particularly for issuers of speculative-grade bonds.     

Partial differential equations for Asian option prices

In this article, we consider fixed and floating strike European style Asian call and put options. For such options, there is no convenient closed-form formula for the prices. Previously, Rogers and Shi, Vecer, and Dubois and Lelièvre have derived partial differential equations with one state variable, with the stock price as numeraire, for the option prices. In this paper, we derive a whole family of partial differential equations, each with one state variable with the stock price as numeraire, from which Asian options can be priced. Any one of these partial differential equations can be transformed into any other. This family includes four partial differential equations which have a particularly simple form including the three found by Rogers and Shi, Vecer, and Dubois and Lelièvre. Our analysis includes the case of a dividend yield; we also include the case of in progress Asian options with floating strike, whereby we discuss the new equation proposed by Vecer, which uses the average asset as numeraire. We perform an error analysis on the four special partial differential equations and Vecer’s new equation and find that their truncation errors are all of the same order. We also perform numerical comparisons of the five partial differential equations and conclude, as expected, that Vecer’s equations and that of Dubois and Lelièvre do better when the volatility is low but that with higher volatilities the performance of all five equations is similar. Vecer’s equations are unique in possessing a certain martingale property and as they perform numerically well or better than the others, must be considered the preferred choice.     

Modelling electricity prices: a time change approach

To capture mean reversion and sharp seasonal spikes observed in electricity prices, this paper develops a new stochastic model for electricity spot prices by time changing the Jump Cox-Ingersoll-Ross (JCIR) process with a random clock that is a composite of a Gamma subordinator and a deterministic clock with seasonal activity rate. The time-changed JCIR process is a time-inhomogeneous Markov semimartingale which can be either a jump-diffusion or a pure-jump process, and it has a mean-reverting jump component that leads to mean reversion in the prices in addition to the smooth mean-reversion force. Furthermore, the characteristics of the time-changed JCIR process are seasonal, allowing spikes to occur in a seasonal pattern. The Laplace transform of the time-changed JCIR process can be efficiently computed by Gauss–Laguerre quadrature. This allows us to recover its transition density through efficient Laplace inversion and to calibrate our model using maximum likelihood estimation. To price electricity derivatives, we introduce a class of measure changes that transforms one time-changed JCIR process into another time-changed JCIR process. We derive a closed-form formula for the futures price and obtain the Laplace transform of futures option price in terms of the Laplace transform of the time-changed JCIR process, which can then be efficiently inverted to yield the option price. By fitting our model to two major electricity markets in the US, we show that it is able to capture both the trajectorial and the statistical properties of electricity prices. Comparison with a popular jump-diffusion model is also provided.     

The intraday determination of liquidity in the NYSE LIFFE equity option markets

We exploit an extensive high-frequency data set of all individual equity options trading at New York Stock Exchange London International Financial Futures and Options Exchange (Amsterdam, London and Paris) in order to study the determination of liquidity during the trading day. In particular, we focus on two main aspects of option liquidity: (i) the intraday behaviour of equity option liquidity and its determinants and (ii) the influence of macroeconomic events and commonality on intraday equity option liquidity. Inventory management models cannot explain the intraday variation in option spreads and depths. Instead, we show that the option liquidity measures are strongly correlated with option volatility. Increases in volatility are associated with decreases in liquidity, a finding that is in line with information asymmetry models and the derivatives hedging theory. However, the relationship between spreads and volume varies across the three markets. Option liquidity reacts strongly to macroeconomic news announcements, especially US events. The average systematic liquidity component is 12% for Amsterdam, 14% for London and 16% for Paris.     

Distress Risk,Growth and Earnings Quality

We extend and complement prior work by investigating the earnings quality of firms with different financial health characteristics and growth prospects. By using three alternative measures of default likelihood and two alternative measures of growth options, without being limited to a specific event, we provide a more comprehensive setup for analysing the earnings characteristics of the universe of firms than examining distressed firms with persistent losses, dividend reductions or bankruptcy‐filings. Our dataset consists of 15,049 healthy U.S. firms over the period 1990–2004. Results show that the relation between earnings quality and financial health is not monotonic. Distressed firms have a low level of earnings timeliness for bad news and a high level for good news, and manage earnings toward a positive target more frequently than healthy firms. On the other hand, healthy firms have a high level of earnings timeliness for bad news. Growth aspects play an important role in a firm's ability to manage earnings. In contrast to the findings of prior studies, growth firms have greater earnings timeliness for bad news, whereas value firms manage earnings toward a positive target more frequently than growth firms.     

Optimal Investment Decisions for Two Positioned Firms Competing in a Duopoly Market with Hidden Competitors

This paper extends the literature dealing with the option to invest in a duopoly market for a leader‐follower setting. A restrictive assumption embodied in the models in the current literature is that investment opportunities are semi‐proprietary in that the two identified or positioned firms are guaranteed to hold at least the follower's position. More competition is realistically captured in our model by introducing the concept of hidden rivals so that the places in the market can be taken not only by positioned firm but also by these hidden competitors. The value functions and the optimal triggers for the positioned firms differ materially in settings with(out) the presence of hidden rivals. Unlike existing models, our model allows for (a)symmetric market shares and investment costs for the leader and the follower. Cooperative entrance by the two positioned firms is also modelled.     

养老基金个人投资选择权的理论阐释与实践发展

国外养老基金个人投资选择权的理论阐释与实践发展表明,职工并不能作为"理性人"在养老基金投资运营中实现收益最大化,并进而揭示出养老基金个人投资选择权的两个主要发展趋势,即"管理机构选择权"模式中个人在投资机构问的转移率与该国人均收入水平负相关,以及"投资基金选择权"模式中个人参与率下降趋势明显.因此,如果我国企业年金设置...     

The Real Options Component and Market Value of Taiwan Technological Companies

Real options valuation has been applied in real investment extensively. However the empirical researches of real options components’ value are seldom studied. This study uses the panel data model to test whether the stock prices of Taiwan listed companies reflect investor’s expectations regarding the value of real options. This article demonstrates that investors cannot ignore the real options components when evaluating stock market value. The results also confirm that the proportion of a firm’s market value not due to assets-in-place is significantly and positively related to the variables of stock beta, skewness of stock returns, size, capital stock, and research and development. In addition, firms with lower firm life cycle have a higher real options value.