Nonstationarity of efficient finance markets: FX market evolution from stability to instability

Real financial markets are uncertain on the shortest trading time scales, therefore trading translates into noise. We discuss the pair correlations of detrended returns necessary to understand financial markets. Efficient markets and equilibrium markets generate conflicting pair correlations. B. Eichengreen [B. Eichengreen, Globalizing Capital,: A History of the International Monetary System, Princeton, Princeton, 1998] argues that FX speculation was stabilizing before WWI. In contrast, our recent empirical analysis shows that we can model FX markets in our present era as nonstationary/unstable and efficient (meaning hard or impossible to beat). We can model pre-WWI non-efficient equilibrium FX dynamics from a closely related theoretical standpoint. Our main points are that deregulated markets are described by a nonstationary process with uncorrelated, nonstationary increments, and that a stationary market (equilibrium market) is mutually exclusive with an unregulated, efficient market. In short, stability and deregulation are mutually exclusive ideas. We review a simple, empirically deduced model of the unstable diffusive nature of volatile FX market dynamics. All information of interest is encoded in the variable diffusion coefficient defining the observed martingale process.     

Activist monetary policy and exchange-rate overshooting: The Deutsche mark/dollar rate

After a decade of generalized floating, it is clear that bilateral exchange rates exhibit more variability than the economic aggregates—relative prices, incomes, and money supplies—which generally comprise the fundamentals of theories of exchange-rate determination. Dornbusch's overshooting hypothesis is the best known explanation of this phenomenon. This paper shows that accommodative monetary policy (with respect to prices) has the potential to cause the economy to switch from exchange rate overshooting to undershooting. Using constrained maximum likelihood methods, the model is estimated for Germany and the United States. The results provide strong evidence in support of the overshooting hypothesis for the Deutsche mark/dollar exchange rate.     

Dynamical clustering of exchange rates

We use techniques from network science to study correlations in the foreign exchange (FX) market during the period 1991–2008. We consider an FX market network in which each node represents an exchange rate and each weighted edge represents a time-dependent correlation between the rates. To provide insights into the clustering of the exchange-rate time series, we investigate dynamic communities in the network. We show that there is a relationship between an exchange rate's functional role within the market and its position within its community and use a node-centric community analysis to track the temporal dynamics of such roles. This reveals which exchange rates dominate the market at particular times and also identifies exchange rates that experienced significant changes in market role. We also use the community dynamics to uncover major structural changes that occurred in the FX market. Our techniques are general and will be similarly useful for investigating correlations in other markets.     

南非外汇期货市场发展及其借鉴意义

作为金砖五国成员之一,近年来南非外汇市场发展令人瞩目。其场外市场交易量占比相对较高,包括外汇期货在内的场内市场产品创新活跃,贴近市场需求。文章分别考察南非场内外外汇市场的运行机制,及其外汇市场整体监管架构与分工协作机制,并从促进场内外市场协调发展、结合市场需求推进产品创新等方面,总结了其对于完善一国外汇市场发展的相关启示。     

A Variance-Ratio Test of Random Walks in Foreign Exchange Rates

The separate variance-ratio tests under homoscedasticity and heteroscedasticity both provide evidence rejecting the random walk hypothesis, using five pairs of weekly nominal exchange rate series over the period from August 7, 1974 to March 29, 1989. The rejections cast doubt on the random walk hypothesis in exchange rates, which has received support in the existing literature. Furthermore, since the rejections are robust to heteroscedasticity, they suggest autocorelations of weekly increments in the nominal exchange rate series, which may be consistent with the exchange rate overshooting or undershooting phenomenon.     

The time-varying diversifiability of corporate foreign exchange exposure

Estimating comovement measures for a large set of bilateral foreign exchange (FX) rates, I explore the relation between firm-level FX exposure and its time-varying diversifiability. For a sample of U.S. firms, the magnitude of FX exposure appears to increase during periods of low currency risk diversifiability. Additional results suggest that the introduction of the euro exacerbated the effect of diversifiability on developed market currency exposure. Moreover, the low diversifiability of emerging market currencies seems to have a stronger effect on FX exposure than the low diversifiability of developed market currencies.     

FX Trading and Exchange Rate Dynamics

I examine the sources of exchange rate dynamics by focusing on the information structure of FX trading. This structure permits the existence of an equilibrium distribution of transaction prices at a point in time. I develop and estimate a model of the price distribution using data from the Deutsche mark/dollar market that prroduces two striking results:(1) Much of the short-term volatility in exchange rates comes from sampling the heterogeneous trading decisions of dealers in a distribution that, under normal market conditions, changes comparatively slowly; (2) public news is rarely the predominant source of exchange rate movements over any horizon.     

The loanable funds theory and the dynamics of exchange rates: The Mundell model revisited

This paper shows that Mundell's model of perfect capital mobility is logically consistent only in the framework of the loanable funds theory. It then develops a loanable funds version of the Mundell model and shows that exchange rate overshooting or undershooting naturally occurs in this ‘corrected’ version of the Mundell model.     

Conditional volatility persistence and volatility spillovers in the foreign exchange market

I investigate the magnitudes and determinants of volatility spillovers in the foreign exchange (FX) market, using realized measures of volatility and heterogeneous autoregressive (HAR) models. I confirm both meteor shower effects (i.e., inter-regional volatility spillovers) and heat wave effects (i.e., intra-regional volatility spillovers) in the FX market. Furthermore, I find that conditional volatility persistence is the dominant channel linking the changing market states of each region to future volatility and its spillovers. Market state variables contribute to more than half of the explanatory power in predicting conditional volatility persistence, with the model that calibrates volatility persistence and spillovers conditionally on market states performing statistically and economically better. The utilization of market state variables significantly extends our understanding of the economic mechanisms of volatility persistence and spillovers and sheds new light on econometric techniques for volatility modeling and forecasting.     

Carry Trades,Order Flow,and the Forward Bias Puzzle

We investigate the relation between foreign exchange (FX) order flow and the forward bias. We outline a decomposition of the forward bias according to which a negative correlation between interest rate differentials and order flow creates a time‐varying risk premium consistent with that bias. Using 10 years of data on FX order flow, we find that more than half of the forward bias is accounted for by order flow—with the rest being explained by expectational errors. We also find that carry trading increases currency‐crash risk in that order flow generates negative skewness in FX returns.     

2011年7月银行间市场运行报告

2011年7月,银行间市场平稳运行,交易稳步增长。主要特点是：货币市场利率震荡下行,银行间国债收益率曲线上移明显;外汇即期市场交易延续活跃,外汇掉期曲线整体上移,汇率升值预期减弱,人民币外汇期权交易进一步活跃。人民币外汇掉期、远期净额清算试运行,净额清算业务向衍生品市场延伸。     

Tick size,NYSE rule 118, and ex-dividend day stock price behavior

Bali and Hite (1998) and Dubofsky (1992) propose models in which market microstructure effects play a role in the ex-dividend day price drop anomaly. Bali and Hite suggest that the anomaly is caused solely by price discreteness, while Dubofsky suggests that NYSE Rule 118 is also involved. We test these models by examining cum- to ex-day price drops during the one-eighth, one-sixteenth, and decimal tick size regimes. While the evidence is qualitatively consistent with Dubofsky's predictions, neither model is satisfactory in a quantitative sense. One of our main empirical findings is that no significant decline was evident in the magnitude of the ex-day anomaly after the tick size reduction.     

The effect of excessively elastic expectations on exchange-rate volatility in the Dornbusch overshooting model

Bilson has described the empirical finding that the forward exchange rate overestimates the speed of return to equilibrium as a finding of ‘excessive speculation’, and has drawn implications for the volatility of the exchange rate. The present paper pursues this tack within the sticky-price monetary model made famous by Dornbusch. It is shown theoretically that if the market overestimates the speed of adjustment, the degree of overshooting is reduced. In this sense ‘excessive speculation’ leads to reduced volatility.     

The market microstructure approach to foreign exchange: Looking back and looking forward

Research on foreign exchange market microstructure stresses the importance of order flow, heterogeneity among agents, and private information as crucial determinants of short-run exchange rate dynamics. Microstructure researchers have produced empirically-driven models that fit the data surprisingly well. But FX markets are evolving rapidly in response to new electronic trading technologies. Transparency has risen, trading costs have tumbled, and transaction speed has accelerated as new players have entered the market and existing players have modified their behavior. These changes will have profound effects on exchange rate dynamics. Looking forward, we highlight fundamental yet unanswered questions on the nature of private information, the impact on market liquidity, and the changing process of price discovery. We also outline potential microstructure explanations for long-standing exchange rate puzzles.     

Heterogeneous real-time trading strategies in the foreign exchange market

The foreign exchange (FX) market is worldwide, but the dealers differ in their geographical locations (time zones), working hours, time horizons, home currencies, access to information,transaction costs, and other institutional constraints. The variety of time horizones is large: from intra-day dealers, who close their positions every evening, to long-term investors and central banks. Depending on the constraints, the different market participats need different strategies to reach their goal, which is usually maximizing the profit, or rather a utility function including risk. Different intra-day trading strategies can be studied only if high-density data are available. Oslen & Associates (O & A) has collected and analysed large amounts of FX quotes by market makers around the clock (up to 5000 non-equally spaced prices per day for the German mark against US$). Based on these data, a set of real-time intra-day trading models has been developed. These models give explicit trading recommendations under realistic constraints. They are allowed to trade only during the opening hours of a market, depending on the time zone and local holidays. The models have been running real-time for more than three years, thus leading to an ex ante test. The test results, obtained with a risk-sensitive performance measure, are presented. All these trading models are profitable, but they differ in their risk behaviour and dealing frequency. If a certain profitable intra-day algorithm is tested with different working hours, its success can considerably change. A systematic study shows that the best choice of working hours is usually when the most important markets for the particular FX rate are active. All the results demonstrate that the assumption of a homogeneous 24-hour FX market with identical dealers, following an identical ‘rational expectation’, is far from reality. To explain the market dynamics, a heterogeneous model of the market with different types of dealers is more appropriate.     

Speculator activity and the cross-asset predictability of FX returns

This paper tests the gradual information diffusion hypothesis, which suggests that information spreads gradually across asset markets, to explain the role of speculator activity in the cross-asset return predictability of foreign exchange (FX) market strategies. We argue that the activity of speculators increase the rate of information diffusion across asset markets. Hence, we expect the predictive effect from the equity and commodity markets on FX market strategies to be weaker when speculators are active in the FX market. Our results show that, when speculator activity is high, the equity market's ability to predict the FX market dissipates, but not to the same extent as for the commodity market. Our findings suggest that speculators play a vital role in enhancing informational efficiency in the FX market.     

远期结售汇业务发展现状及政策建议

随着人民币汇率弹性的逐步增强,汇率风险的防范问题已日显重要,外汇衍生品市场的发展继而成为我们关注的焦点。文章介绍了湖北省远期结售汇业务的发展现状及成因,从供求关系、交易方式等角度分析了当前制约业务发展的因素,并从鼓励金融创新和进一步完善汇率形成机制的角度,提出相应的市场发展建议。     

外汇期权信息含量与在岸离岸市场效率

央行在“8·11”汇改后放松了汇率中间价的管理,采用更为市场化的方式形成中间价,这种变化对于人民币汇率衍生品市场的影响尚属未知。为此,本文从人民币期权组合的Black-Scholes隐含波动率历史报价数据中提取出在岸、离岸市场人民币期权的无模型隐含波动率和风险中性偏度,在将样本划分为汇改前后三个不同的阶段的基础上,检验了期权隐含指标对未来汇率分布的预测能力。实证结果表明,在“8·11”汇改之后,随着人民币中间价形成机制变得更加市场化,期权价格中包含了越来越多关于未来汇率分布的信息,在岸和离岸期权市场的信息效率都有显著提高,意味着人民币中间价形成机制的市场化能显著提升我国金融市场效率。因此,在兼顾金融安全的角度上,稳步促进人民币中间价形成机制市场化进程将有利于我国金融市场效率的提高。     

市场运行平稳,人民币持续走强 2007年银行间外汇市场运行报告

2007年银行间外汇市场运行平稳。与2006年相比,外汇远期交易量增长六成,外汇掉期交易量增长三倍多,外币对交易量增长近两成,外币拆借交易量下降近五成。2007年,人民币兑美元和港币继续保持升值趋势,兑日元和英镑升值、兑欧元贬值。与2006年年末中间价比,2007年末人民币兑美元汇率中间价累计升值6.90%。与2005年汇改当日中间价比,人民币累计升值13.31%。     

A class of Lévy process models with almost exact calibration to both barrier and vanilla FX options

Vanilla (standard European) options are actively traded on many underlying asset classes, such as equities, commodities and foreign exchange (FX). The market quotes for these options are typically used by exotic options traders to calibrate the parameters of the (risk-neutral) stochastic process for the underlying asset. Barrier options, of many different types, are also widely traded in all these markets but one important feature of the FX options markets is that barrier options, especially double-no-touch (DNT) options, are now so actively traded that they are no longer considered, in any way, exotic options. Instead, traders would, in principle, like to use them as instruments to which they can calibrate their model. The desirability of doing this has been highlighted by talks at practitioner conferences but, to our best knowledge (at least within the realm of the published literature), there have been no models which are specifically designed to cater for this. In this paper, we introduce such a model. It allows for calibration in a two-stage process. The first stage fits to DNT options (or other types of double barrier options). The second stage fits to vanilla options. The key to this is to assume that the dynamics of the spot FX rate are of one type before the first exit time from a ‘corridor’ region but are allowed to be of a different type after the first exit time. The model allows for jumps (either finite activity or infinite activity) and also for stochastic volatility. Hence, not only can it give a good fit to the market prices of options, it can also allow for realistic dynamics of the underlying FX rate and realistic future volatility smiles and skews. En route, we significantly extend existing results in the literature by providing closed-form (up to Laplace inversion) expressions for the prices of several types of barrier options as well as results related to the distribution of first passage times and of the ‘overshoot’.