Are Co-integrated Stock Prices Consistent with the Efficient Market Hypothesis?

This paper responds to the unsatisfactory argument that there is no correspondence between co-integration and the efficient market hypothesis. A law of one co-integrating vector of prices is proposed for the exchange rate and domestic and overseas stock prices. Markets must therefore be efficient in long-run equilibrium because no arbitrage opportunities exist. However, arbitrage activity via the disequilibrium error correction allows above-average (risk-adjusted) returns to be earned in the short run. The elimination of these arbitrage opportunities means that stock market inefficiency in the short run ensures stock market efficiency in the long run.     

The role of independence in the Green-Lin Diamond-Dybvig model

Green and Lin study a version of the Diamond-Dybvig model with a finite number of agents, independence (independent determination of each agent's type), and sequential service. For special preferences, they show that the ex ante first-best allocation is the unique equilibrium outcome of the model with private information about types. Via a simple argument, it is shown that uniqueness of the truth-telling equilibrium holds for general preferences—and, in particular, for a constrained-efficient allocation whether first-best or not. The crucial assumption is independence.     

Inflation, investment and economic performance: The role of internal financing

This paper studies a link between inflation and economic activity that is built on two hypotheses. First, firms mitigate informational frictions in financial markets by accumulating retained earnings over a period of time. Second, firms allocate earnings among three competing uses - dividends, current investment, and the accumulation of internal funds - and inflation directly distorts this allocation decision as well as the real value of accumulated internal funds. The model predicts that the level of inflation - both unanticipated and expected inflation - as well as the variability of inflation distort firms’ internal financing decisions, increases frictions in financial markets, reduces the level and efficiency of investment, and reduces aggregate output. The marginal effects of inflation are increasing in the inflation rate.     

Collateral constraints and the amplification mechanism

Kiyotaki and Moore (J. Polit. Economy 105 (1997) 211) have offered a theory for how common shocks to credit-constrained firms are amplified through changes in collateral values and transmitted as fluctuations in output. I clarify and extend their model by showing that their collateral amplification mechanism is not robust to the introduction of markets that allow these firms to hedge against common shocks. A theory of incomplete hedging is proposed in which the supply of hedging available in the economy is constrained by the aggregate value of collateral. I illustrate how the constraint reinstates amplification effects and discuss empirical implications of this new mechanism.     

On some criteria for the formulation and testing of economic growth models

This paper presents a methodology for the formulation and testing of economic growth models. The model selected includes two production sectors with physical and human capital accumulation. These capital stocks are associated with spillover effects in the production of the physical good and in the accumulation of both factors.     

Government guarantees and self-fulfilling speculative attacks

We develop a model in which government guarantees to banks’ foreign creditors are a root cause of self-fulfilling twin banking-currency crises. Absent guarantees, such crises are not possible. In the presence of guarantees banks borrow foreign currency, lend domestic currency and do not hedge the resulting exchange rate risk. With guarantees, banks will also renege on their foreign debts and declare bankruptcy when a devaluation occurs. We assume that the government is unable or unwilling to fully fund the resulting bailout via an explicit fiscal reform. These features of our model imply that government guarantees lead to self-fulfilling banking-currency crises.     

电子商务企业物流模式的经济学研究

电子商务企业对传统的物流提出了挑战．成为物流发展的强劲动力。本文从经济学理论角度对电子商务企业物流模式的选择进行了探讨：从对总成本的节约出发建立了企业自营与外包物流决策的成本模型．并分析了在电子商务的影响下该模型中成本因素的变化。得出第三方物流将是电子商务企业的好选择。     

A corporate balance-sheet approach to currency crises

This paper presents a general equilibrium currency crisis model of the ‘third generation’, in which the possibility of currency crises is driven by the interplay between private firms’ credit-constraints and nominal price rigidities. Despite our emphasis on microfoundations, the model remains sufficiently simple that the policy analysis can be conducted graphically. The analysis hinges on four main features (i) ex post deviations from purchasing power parity; (ii) credit constraints a la Bernanke-Gertler; (iii) foreign currency borrowing by domestic firms; (iv) a competitive banking sector lending to firms and holding reserves and a monetary policy conducted either through open market operations or short-term lending facilities. We derive sufficient conditions for the existence of a sunspot equilibrium with currency crises. We show that an interest rate increase intended to support the currency in a crisis may not be effective, but that a relaxation of short-term lending facilities can make this policy effective by attenuating the rise in interest rates relevant to firms.     

Overnight borrowing, interest rates and extreme value theory

We examine the dynamics of extreme values of overnight borrowing rates in an inter-bank money market before a financial crisis during which overnight borrowing rates rocketed up to (simple annual) 4000 percent. It is shown that the generalized Pareto distribution fits well to the extreme values of the interest rate distribution. We also provide predictions of extreme overnight borrowing rates using pre-crisis data. The examination of tails (extreme values) provides answers to such issues as to what are the extreme movements to be expected in financial markets; is there a possibility for even larger movements and, are there theoretical processes that can model the type of fat-tails in the observed data? The answers to such questions are essential for proper management of financial exposures and laying ground for regulations.     

应用电法新装置勘探二维与三维地电体

本文通过对新装置条件下位场特征的分析,应用边界单元法及解析法的计算结果,发现当二维或三维电性不均匀体与测量电极位于背景场同一等位面时,视电阻率异常反映最明显。从而提出了圆弧交会法确定二维或三维地电体中心理深的方法,并给出了若干计算实例。结果表明,此方法简便有效且精度较高。