Are Different-Currency Assets Imperfect Substitutes?

This paper provides a new test for whether different-currency assets are imperfect substitutes. Past work on imperfect substitutability in foreign exchange falls into two groups: (1) tests using measures of asset supply and (2) tests using measures of central-bank asset demand. We address the demand side, but we use a broad measure of public demand rather than focusing on demand by central banks. Under floating rates, changing public demand has no direct effect on monetary fundamentals, current or future. This provides an opportunity to test for price effects from imperfect substitutability. We develop and estimate a micro portfolio balance model that has both Walrasian and microstructure features. Price effects from imperfect substitutability are clearly present: the immediate price impact of public trades is 0.44 percent per $1 billion (of which, about 80 percent persists indefinitely). This estimate is applicable to intervention trades in the special case when they are indistinguishable from private trades (i.e., when interventions are sterilized, anonymous, and provide no monetary-policy signal).

Portfolio Balance, Price Impact, and Secret Intervention

This paper tests the portfolio-balance approach to exchange rate determination in a new way. Past work on portfolio balance in foreign exchange falls into two groups: (1) tests using measures of asset supply and (2) tests using measures of central-bank asset demand. We address the demand side, but we use a broad measure of public demand, rather than focusing on demand by central banks. Under floating rates, changing public demand has no direct effect on interest rates, current or future. This provides an opportunity to test for portfolio-balance effects on price. We develop and estimate a micro portfolio-balance model that has both Walrasian and microstructure features. Portfolio-balance effects are clearly present: the immediate price impact of public trades is 0.44 percent per $1 billion (of which, about 80 percent persists indefinitely). This estimate is applicable to central-bank trades as well, as long as they are sterilized, secret, and provide no monetary-policy signal. Intervention of this type is most effective when the flow of macroeconomic news is strong.

Are Different-Currency Assets Imperfect Substitutes?

This paper provides a new test for whether different-currency assets are imperfect substitutes. The test exploits that under floating rates, changing public currency demand has no direct effect on monetary fundamentals, current or future. Price effects from imperfect substitutability are clearly present: the immediate price impact of public trades is 0.44 percent per 1 billion dollar (of which, about 80 percent persists indefinitely). This estimate is applicable to intervention trades in the special case when they are indistinguishable from private trades (i.e., when interventions are sterilized, anonymous, and provide no monetary-policy signal).

Exchange Rate Fundamentals and Order Flow

We address whether transaction flows in foreign exchange markets convey fundamental information. Our GE model includes fundamental information that first manifests at the micro level and is not symmetrically observed by all agents. This produces foreign exchange transactions that play a central role in information aggregation, providing testable links between transaction flows, exchange rates, and future fundamentals. We test these links using data on all end-user currency trades received at Citibank over 6.5 years, a sample sufficiently long to analyze real-time forecasts at the quarterly horizon. The predictions are borne out in four empirical findings that define this paper's main contribution: (1) transaction flows forecast future macro variables such as output growth, money growth, and inflation, (2) transaction flows forecast these macro variables significantly better than the exchange rate does, (3) transaction flows (proprietary) forecast future exchange rates, and (4) the forecasted part of fundamentals is better at explaining exchange rates than standard measured fundamentals.

Exchange Rate Fundamentals and Order Flow (July 2004)

This paper addresses the striking ability of transaction flows to explain exchange rate movements. Specifically, we examine whether this arises because transaction flows convey incremental information about fundamentals. If so, then these flows should affect price upon their realization and observation by price setters (marketmakers). Our model is a simple general equilibrium model of information aggregation that provides---in a setting of incomplete markets---a utility-based present-value representation for exchange rates. The model produces testable implications for the relationships between realized transaction flows, current and future exchange rate returns, and future fundamentals (e.g., money supplies). We then bring these implications to the data, making use of a new dataset covering over six years of transactions (which permits estimation at the monthly frequency). We find strong contemporanous effects of transaction flows on exchange rates, corroborating past findings. More importantly, we present four key findings that are both new to the literature and supportive of our model: (1) transaction flows forecast (Granger cause) future macroeconomic variables such as money growth, output growth, and inflation, (2) transaction flows forecast future exchange rates changes, and do so more effectively than forward discounts, (3) the future exchange rate components that current flows forecast are primarily the future non-flow-driven components, and (4) though flows convey new information about future fundamentals, much of this information is still not impounded in the exchange rate 9 months later. The slow pace of learning implies that abstracting from information aggregation---as is standard in exchange rate economics---is not innocuous.Exchange Rate Dynamics, Microstructure, Order Flow.

How is Macro News Transmitted to Exchange Rates? (December 2003)

This paper tests whether macroeconomic news is transmitted to exchange rates via the transactions process and if so, what share occurs via transactions versus the traditional direct channel. We identify the link between order flow and macro news using a heteroskedasticity-based approach, a la Rigobon and Sack (2002). In both daily and intra-daily data, order flow varies considerably with macro news flow. At least half of the effect of macro news on exchange rates is transmitted via order flow.

Meese-Rogoff Redux: Micro-Based Exchange Rate Forecasting

This paper compares the true, ex-ante forecasting performance of a micro-based model against both a standard macro model and a random walk. In contrast to existing literature, which is focused on longer horizon forecasting, we examine forecasting over horizons from one day to one month (the one-month horizon being where micro and macro analysis begin to overlap). Over our 3-year forecasting sample, we find that the micro-based model consistently out-performs both the random walk and the macro model. Micro-based forecasts account for almost 16 per cent of the sample variance in monthly spot rate changes. These results provide a level of empirical validation as yet unattained by other models. Though our micro-based model out-performs the macro model, this does not imply that past macro analysis has overlooked key fundamentals: our structural interpretation using a fundamentals-based model shows that our findings are consistent with exchange rates being driven by standard fundamentals.Exchange rates, forecasting, Meese and Rogoff, microstructure, order flow

Oxygen ion dynamics in the Earth's ring current: Van Allen probes observations

Oxygen (O+) enhancements in the inner magnetosphere are often observed during geomagnetically active times, such as geomagnetic storms. In this study, we quantitatively examine the difference in ring current dynamics with and without a substantial O+ ion population based on almost 6 years of Van Allen Probes observations. Our results have not only confirmed previous finding of the role of O+ ions to the ring current but also found that abundant O+ ions are always present during large storms when sym-H < -60 nT without exception, whilst having the pressure ratio () between O+ and proton (H+) larger than 0.8 and occasionally even larger than 1 when L < 3. Simultaneously, the pressure anisotropy decreases with decreasing sym-H and increasing L shell. The pressure anisotropy decrease during the storm main phase is likely related to the pitch angle isotropization processes. In addition, we find that increases during the storm main phase and then decreases during the storm recovery phase, suggesting faster buildup and decay of O+ pressure compared to H+ ions, which are probably associated with some species dependent source and/or energization as well as loss processes in the inner magnetosphere.Accepted manuscrip