Credit: Zehao Li

I am Steve Wu (吳栢洋), an Assistant Professor in the Economics Department of University of California, San Diego (UCSD).

Research Interests: International Macro/Finance, Monetary Economics


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Liquidity and Exchange Rates: An Empirical Investigation with Charles Engel 

The Review of Economic Studies, Volume 90, Issue 5, October 2023, Pages 2395–2438  [Publisher free link]

[Appendix A]  [Appendix B]  [Data]  [Replication package] [Non-technical summary on EconBrowser]

We find strong empirical evidence that the liquidity yield on government bonds in combination with standard economic fundamentals can well account for nominal exchange rate movements. We find impressive evidence that changes in the liquidity yield are significant in explaining exchange rate changes for all the G10 countries, and we stress that the U.S. dollar is not special in this relationship. We show how these relationships arise out of a canonical two-country New Keynesian model with liquidity returns. Additionally, we find a role for sovereign default risk and currency swap market frictions.

Forecasting the U.S. Dollar in the 21st Century with Charles Engel 

Journal of International Economics Volume 141, March 2023, 103715 [Publisher link]

[Online Appendix] [Replication package]

A long-standing puzzle is the near-random-walk behavior of exchange rates. Recent literature has proposed models to forecast exchange rates at medium- and long-horizons. Such tests suffer from small-sample bias but inferring the true test distribution is difficult. We propose two approaches to address the problem. First, since economists are interested in the value of economic models versus purely statistical models, we propose a horse-race that pits the economic models not against the random walk, but against the forecasts from the level of the exchange rate. These economic models are challenged because the level of the exchange rate appears to be a more powerful predictor than “global risk” variables. We also propose a second more general but less powerful test. But with both tests we demonstrate using bootstraps that the random walk cannot be rejected, so the predictive power of the lagged exchange rate and many other variables is illusory. 

The Uncovered Interest Rate Parity Puzzle, Exchange Rate Forecasting, and Taylor Rules with Charles Engel, Chang Liu, Chenxin Liu and Dohyeon Lee

Journal of International Money and Finance 95, July 2019, 317-331 [Publisher link]

Recent research has found that the Taylor-rule fundamentals have power to forecast changes in U.S. dollar exchange rates out of sample. Our work casts some doubt on that claim. However, we find strong evidence of a related in-sample anomaly. When we include U.S. inflation in the well-known uncovered interest parity regression of the change in the exchange rate on the interest-rate differential, we find that the inflation variable is highly significant and the interest-rate differential is not. Specifically, high U.S. inflation in one month forecasts dollar appreciation in the subsequent month. We introduce a model in which a Taylor rule determines monetary policy, but in which not only monetary shocks but also liquidity shocks drive nominal interest rates. This model can potentially account for the empirical findings. 

Working papers

Using firm-level data from emerging markets, we examine the effect of US dollar debt issuance on corporate risk-taking in the low-interest-rate environment after the global financial crisis. We find that the dollar debt issuance significantly increases issuers’ risk-taking. This effect is more pronounced when global banks have a stronger risk appetite. Following the dollar debt issuance, issuers significantly increase their investment spending but wind up with lower investment efficiency and larger financial vulnerability. Moreover, non-issuers also exhibit increased risk-taking when faced with rising intra-industry competition pressure from issuers. The intra-industry cross-sectional risk distributions are more tilted towards the downside. 

Previous title: Carry Trades and Precautionary Saving: The Use of Proceeds from Foreign Currency Debt Issuance

The surge in foreign currency (FC) corporate debt in emerging economies has sparked concerns about macroeconomic stability, heightened by speculation about non-financial firms engaging in carry trades. Using firm-level data on the currency denomination of both assets and liabilities, we find evidence of firms' carry trades: firms save in local currency liquid assets and earn higher interest income after issuing short-term FC debt. They also set aside FC liquid assets as FX risk buffers. A large degree of heterogeneity in incentives is observed. Notably, listed firms participate more in carry trades and allocate less FX risk buffers than non-listed firms.

Abstract We construct a two-country New Keynesian model in which US government debt has an advantage as a superior collateral asset on the balance sheets of banks. The model can account for the observed exchange rate and external position behavior of the US. In our model, the US enjoys an “exorbitant privilege” as its government bonds are desired by banks both in the US and abroad as superior collateral. In times of global stress, the dollar appreciates since the demand for high-quality collateral drives up the “convenience yield” earned by US government bonds. There is “retrenchment” - each country reduces its holdings of foreign assets - a critical determinant of which is the endogenous response of prices and returns. In addition, the model displays a US real exchange rate appreciation despite that domestic absorption in the US falls relative to the rest of the world during a global downturn, thus addressing the “reserve currency paradox” highlighted by Maggiori (2017).

This paper studies the interaction between foreign exchange reserves and the currency composition of sovereign debt in emerging countries. Focusing on inflation targeting countries, we find that holdings of foreign reserves are associated with higher local currency sovereign debt, an exchange rate which is less sensitive to global shocks, and a lower exchange rate risk premium in local currency sovereign spreads. We rationalize these findings within a financially constrained model of a small open economy. The Sovereign values local currency debt as a hedge against endowment risk, but since the exchange rate tends to depreciate in times of global downturns, risk averse international investors charge an additional currency risk premium on this debt. When a country optimally uses foreign reserves to lean against the wind in response to global shocks, this dampens the response of the exchange rate, providing insurance for the global investor. By reducing the risk premium on local currency debt, foreign exchange reserves therefore facilitate a higher share of local currency debt in the sovereign portfolio. Quantitatively, we find the welfare benefits for the sovereign from optimal foreign reserves management can be very large.

Original Sin Redux: A Model-Based Evaluation with Boris Hofmann, Nikhil Patel

This version: Sept 2023  (1st version, April 2021)

Using a two-country model, this paper shows that the shift from foreign currency to local currency external borrowing does not eliminate the vulnerability of EMs to foreign financial shocks but instead results in “original sin redux”. A monetary tightening abroad is propagated to EM financial conditions through a tightening of foreign lenders’ financial constraints, driven in part by currency mismatches on their balance sheets. Foreign exchange intervention and capital flow management measures can mitigate global financial spillovers to EMs in the short run and a larger domestic investor base can reduce the vulnerability in the longer run.

Corporate Balance Sheets and Sovereign Risk Premia

This version: March 2022 (1st version, October 2019)  [OIFM presentation video]

Corporate external debt in emerging countries is very dollarized. We show this could create an externality to the sovereign and is reflected in sovereign spreads. Empirically, decomposing sovereign spreads into their credit default premium (default probability) and credit risk premium components, an increase in foreign-currency corporate debt is associated with a significant increase in the sovereign risk premium but does not change the sovereign default premium. We reconcile both findings in a quantitative model with risk-averse international investors, foreign-currency corporate debt makes the sovereign more likely to default in investors’ bad times when foreign-currency appreciates, thus increases the risk premium.

Work in Progress

This paper develops a high-dimensional vector autoregression framework with common factors regulated by the Lasso method to explore spillovers across sectors and their implications for aggregate inflation persistence in the US. We demonstrate that accounting for sectoral spillover increases inflation persistence, particularly during high inflation episodes. A shock to a sector with a univariate time series of low inflation persistence could induce persistent aggregate inflation, primarily attributable to sectoral spillover. In the data, 13 out of 16 sectors in personal consumption expenditure categories contribute more to the aggregate inflation persistence than to their own inflation persistence.

We document that the lion’s share of the secular decline in long-term interest rates in advanced economies is concentrated within a narrow window around the U.S. FOMC meetings. Global interest rate movements outside the FOMC window are transitory and close to zero on average. Global interest rate movements within the FOMC windows feature a persistent decline with no sign of reversal within 10 years. The U.S. interest rate pass-through to the rest of the world is almost one-to-one during the FOMC window. Exchange rates do not adjust according to uncovered interest parity. The U.S. convenience yield tends to decline during the FOMC windows. The cross-country trend decline in interest rates is associated with a global FOMC trend.