Why do central banks intervene?

Intervention by central banks, in terms of buying and selling foreign currency, has been a major activity in recent years. This paper investigates the motivations for such policy and the evidence for its effectiveness. We use high quality daily data on the dollar amounts of intervention by the central banks of the US and Germany. We also use information on agreed G7 target levels for the $/DM and $/Yen nominal exchange rates. Daily, nominal dollar exchange rate returns are well described as a Martingale-GARCH process, and we find little evidence that the different types of intervention have had much effect on the conditional mean of exchange rate returns. There is some evidence that intervention is associated with slight increases in the volatility of exchange rate returns. While little evidence is found for the effectiveness of intervention, the motivations are more clear. In particular, from the application of probit analysis we find that the probability of intervention is determined by the magnitude of the deviation of the nominal exchange rate from the agreed target level and, to a lesser extent, by the current volatility of exchange rates.     

Central bank interventions and implied exchange rate correlations

This paper examines the effects of the foreign exchange market interventions by the Bank of Japan on the ex ante correlations between the JPY/USD, EUR/USD, and GBP/USD exchange rates. The correlation estimates used in the analysis are derived from the market prices of OTC currency options. The results show that central bank interventions significantly affect the market expectations about future exchange rate co-movements. In particular, we find that interventions tend to temporarily increase the ex ante correlations among the major exchange rates. However, our results also suggest that intervention episodes are associated with lower-than-average levels of exchange rate correlations.     

Central Bank Intervention in USD/INR Market: Estimating Its Reaction Function and Impact on Volatility

Econometric evidence on why central banks intervene in the foreign exchange market and the impact of such intervention has remained inconclusive. We contribute to the literature with evidence from India, a managed float regime that sees consistent monitoring and intervention by Reserve Bank of India, India’s central bank. Estimation of the central bank reaction function shows that increased volatility in the foreign exchange market and misalignment from targeted rates are important objectives behind intervention. The paper further uses the GARCH framework to study how intervention influences exchange rate volatility. We find that intervention in the spot market increases volatility while that in the forward market reduces volatility.     

Reward-to-Risk Ratios in the Treasury-Bill Market

We estimate the ex‐ante reward per unit of spot‐rate volatility (the reward‐to‐risk ratio) for U.S. Treasury bills on a monthly basis and find that these ratios vary predictably over time. Reward‐to‐risk ratios are positively autocorrelated; month‐to‐month changes in these ratios are negatively autocorrelated. Variation in these ratios contributes at least as much variation to ex‐ante excess returns as does variation in interest‐rate volatility. Because ex‐ante volatility and the rewards to volatility vary independently, variation in ex‐ante premiums is greater than the variation attributable to changing volatility alone.     

Central bank FOREX interventions assessed using realized moments

This paper assesses the impact of G3 official central bank interventions on daily realized moments of DEM/USD exchange rate returns obtained from intraday data, 1989–2001. Event studies of the realized moments for the intervention day, the days preceding and following the intervention illustrate the shape of this impact. Rolling regressions results for an AR(FI)MA model for realized moments are used to measure the impact and its significance. The analysis confirms previous empirical findings of a temporary increase of volatility after a coordinated central bank intervention. It highlights new findings on the timing and the temporary nature of the impact of coordinated interventions on exchange rate volatility and on cross-moments between foreign exchange markets.     

Central bank communication and exchange rate volatility: a GARCH analysis

We examine the effects of the Czech National Bank communication, macroeconomic news and interest rate differential on exchange rate volatility using generalized autoregressive conditional heteroscedasticity model. Our results suggest that central bank communication has a calming effect on exchange rate volatility. The timing of central bank communication seems to matter, too, as financial markets respond more to the communication before the policy meetings than after them. Next, macroeconomic news releases are found to reduce exchange rate volatility, while interest rate differential seems to increase it.     

Central bank intervention and exchange rates: the case of Sweden

This paper examines the effect of the Riksbank's currency market interventions on the level and volatility of the SEK/USD and SEK/DEM exchange rates between 1993 and 1996. This is the first study investigating effects on the Swedish krona after the currency peg was abandoned in 1992. To model volatility, both GARCH models and implied volatilities from currency options are used. Some support is found for the idea that interventions affect the exchange-rate level during certain sub periods but, overall, the results are weak. Furthermore, in line with the findings for other countries, little empirical support is found for the hypothesis that central bank intervention systematically decreases exchange rate volatility.     

Japanese foreign exchange intervention and the yen-to-dollar exchange rate: A simultaneous equations approach using realized volatility

We use realized volatility to study the influence of Japanese central bank interventions on the yen-to-dollar exchange rate. A system of equations for returns, logarithmic realized volatility, and interventions provides a comprehensive view on the problem without endogeneity bias, unlike earlier latent variable specifications. We find that during the period 1991 through 1995, interventions of the Japanese monetary authorities could not move the yen-to-dollar rate into the desired direction. We measure an increase in volatility associated with interventions. During the period 1995 through 1998, the estimations are consistent with interventions that successfully influenced returns. After 1998 up to the last intervention episode in 2004, interventions did not have a significant impact on returns but reduced realized exchange rate volatility.     

Determinants of periodic volatility of intraday exchange rates in the Taipei FX Market

Using the periodic GARCH (P-GARCH) model, this paper investigates the cause of the volatility seasonality of intraday Taiwan dollar/U.S. dollar (NTD/USD) exchange rate. We study the intraday volatility of NTD/USD exchange rate by considering impacts from public news arrivals, inventory risk and central bank interventions. The estimation results indicate that news arrivals at the market open may induce traders to adjust their inventory position and result in higher NTD/USD volatility on days with reported central bank interventions.     

The incremental volatility information in one million foreign exchange quotations

The volatility information found in high-frequency exchange rate quotations and in implied volatilities is compared by estimating ARCH models for DM/$ returns. Reuters quotations are used to calculate five-minute returns and hence hourly and daily estimates of realised volatility that can be included in equations for the conditional variances of hourly and daily returns. The ARCH results show that there is a significant amount of information in five-minute returns that is incremental to options information when estimating hourly variances. The same conclusion is obtained by an out-of-sample comparison of forecasts of hourly realised volatility.     

Firm-level effects of asymmetric intervention in foreign exchange markets: Evidence from the Swiss currency floor

In January 2015, the Swiss National Bank (SNB) abandoned the Swiss franc's exchange rate floor against the Euro. This paper is the first to study the firm-level effects of this asymmetric type of central bank intervention in foreign exchange markets. Using weekly stock returns for a sample of Swiss non-financial firms, I find significant reductions in total stock return volatility as well as market risk following the introduction of the currency floor. Accounting for the asymmetric nature of the intervention, I show that the enforcement of this policy solely manifests in a significant reduction of incremental EUR/CHF exchange rate risk exposures of exporting firms, while importing firms experience reductions in proportion to the market portfolio only. Thus, the asymmetric policy design is reflected in asymmetric responses of firm-level currency exposures. All effects, however, do not depend on the extent of business activity in the Eurozone. The overall results suggest that the currency floor was successful in supporting the performance of the Swiss economy by effectively reducing stock return sensitivities to market fluctuations and EUR/CHF exchange rate volatility.     

Conditional covariances and direct central bank interventions in the foreign exchange markets

In this paper, we investigate the effects of central bank interventions (CBIs) on the ex post correlation and covariance of exchange rates. Using a multivariate GARCH model with time-varying conditional covariances, we estimate the effects of CBIs on both the variances and covariance between the yen and the deutsche mark (the Euro) in terms of the US dollar. Our results suggest that coordinated CBIs not only tend to increase the volatility of exchange rates but also explain a significant amount of the covariance between the major currencies. We show that this result can be useful for short-run currency portfolio management.     

Exchange rate volatility across financial crises

This paper studies the impact of global financial turmoil on the exchange rate policies in emerging countries. Spillovers from advanced financial markets to currencies in emerging countries are likely to be exacerbated during crisis periods. To test this hypothesis, we assess the exchange rate policies by currencies’ volatility and investigate their relationship to a global financial stress indicator, measured by the volatility on global markets. We introduce the possibility of nonlinearities by running smooth transition regressions over a sample of 21 emerging countries from January 1994 to September 2009. The results confirm that exchange rate volatility does increase more than proportionally with the global financial stress, for most countries in the sample. We also evidence regional contagion effects spreading from one emerging currency to other currencies in the neighboring area.     

人民币汇率波动与我国通胀、产出波动：一个扩展泰勒曲线的研究

发挥市场供求对汇率的调节作用,增强人民币汇率双向浮动弹性,是当前我国汇率体制改革的主要方向。本文在泰勒曲线的框架下考察人民币汇率波动对我国宏观经济波动和货币政策实施的影响。通过实证研究发现,1994—2006年通货膨胀波动对人民币汇率波动是不敏感的,人民币汇率传递效应不显著,人民币汇率波动对宏观经济波动没有显著的影响;2007年以后人民币汇率波动推动泰勒曲线向内移动,因此更大的人民币汇率弹性对货币政策传导和货币政策有效性是有利的,逐步扩大的人民币汇率弹性区间对我国宏观经济运行是适宜和可接受的。另外人民币汇率波动也使得泰勒曲线更加陡峭,稳定通货膨胀所导致的产出缺口波动减小了,因而更有利于货币政策当局追求一个低而稳定的通胀目标。     

Volatility transmission in emerging European foreign exchange markets

This paper studies the dynamics of volatility transmission between Central European (CE) currencies and the EUR/USD foreign exchange using model-free estimates of daily exchange rate volatility based on intraday data. We formulate a flexible yet parsimonious parametric model in which the daily realized volatility of a given exchange rate depends both on its own lags as well as on the lagged realized volatilities of the other exchange rates. We find evidence of statistically significant intra-regional volatility spillovers among the CE foreign exchange markets. With the exception of the Czech and, prior to the recent turbulent economic events, Polish currencies, we find no significant spillovers running from the EUR/USD to the CE foreign exchange markets. To measure the overall magnitude and evolution of volatility transmission over time, we construct a dynamic version of the Diebold–Yilmaz volatility spillover index and show that volatility spillovers tend to increase in periods characterized by market uncertainty.     

Central bank interventions and jumps in double long memory models of daily exchange rates

In this paper, we estimate ARFIMA–FIGARCH models for the major exchange rates (against the US dollar) which have been subject to direct central bank interventions in the last decades. We show that the normality assumption is not adequate due to the occurrence of volatility outliers and its rejection is related to these interventions. Consequently, we rely on a normal mixture distribution that allows for endogenously determined jumps in the process governing the exchange rate dynamics. This distribution performs rather well and is found to be important for the estimation of the persistence of volatility shocks. Introducing a time-varying jump probability associated to central bank interventions, we find that the central bank interventions, conducted in either a coordinated or unilateral way, induce a jump in the process and tend to increase exchange rate volatility.     

异质预期条件下中央银行沟通对人民币汇率波动的影响

在外汇市场交易者预期异质性的假设条件下,以2005年7月至2015年12月中国人民银行沟通频数和人民币汇率数据为样本,采用异质预期汇率模型考察中央银行沟通对人民币汇率波动的总体影响。研究发现：在异质预期条件下,中央银行沟通通过信息机制和协调机制影响外汇市场交易者的异质预期,从而对人民币汇率波动产生较为显著的影响,但由于我国外汇交易者预期向基本面预期转换的发生概率小于技术分析交易者预期,中央银行沟通对人民币汇率波动的平稳作用效力受到一定的局限。     

A cyclical model of exchange rate volatility

In this paper, we investigate the long run dynamics of the intraday range of the GBP/USD, JPY/USD and CHF/USD exchange rates. We use a non-parametric filter to extract the low frequency component of the intraday range, and model the cyclical deviation of the range from the long run trend as a stationary autoregressive process. We use the cyclical volatility model to generate out-of-sample forecasts of exchange rate volatility for horizons of up to 1 year under the assumption that the long run trend is fully persistent. As a benchmark, we compare the forecasts of the cyclical volatility model with those of the range-based EGARCH and FIEGARCH models of Brandt and Jones (2006). Not only does the cyclical volatility model provide a very substantial computational advantage over the EGARCH and FIEGARCH models, but it also offers an improvement in out-of-sample forecast performance.     

The ‘laissez faire’ bias of managed floating

The government of a small open economy trying to manage its exchange rate faces a ‘time consistency’ problem. If markets expect implementation of the optimal linear intervention rule, the government will be tempted to ‘defect’: knowing this, markets will expect less activism; and, in the discretionary equilibrium, this is what they get. How far this credibility problem can shift discretionary policy towards a free float is shown in two popular models of floating rates. One way of offsetting the ‘laissez faire’ bias of discretionary policy is to appoint a relatively ‘conservative’ central banker: but, as the time period of policy action and precommitment shrinks towards zero, the required conservative bias is found to go towards infinity. Other institutional features — such as central bank reputation, contracts and intermediate targets — may be crucial for successful exchange rate management.     

Central bank interventions and exchange rates: an analysis with high frequency data

We use high frequency data for the mark–dollar exchange rate for the period 1992–1995 to evaluate the effects of central bank interventions on the foreign exchange market. We estimate an unobserved component model that decomposes volatility into non-stationary and stationary parts. Stationary components in turn are decomposed into seasonal and non-seasonal intra-day parts. Our results confirm the view that interventions are not particularly effective. The exchange rate moves in the desired direction for only about 50% of the time, and often with a substantial increase in volatility. The model suggests that the two components, which are affected the most by interventions, are the permanent and the stochastic intra-day.