Charles P. Thomas

Recovering an Asset's Implied PDF from Option Prices: An Application to Crude Oil During the Gulf Crisis

We develop a general method for estimating the implied, martingale equivalent, probability density function (PDF) for futures prices from American options prices. The early exercise feature of American options precludes expressing the price of the option in terms of the PDF. There exist tight bounds for the price of American options in terms of the PDF. We demonstrate how these bounds, together with observed option prices, can be used to estimate the parameters of the PDF. We estimate the distribution for crude oil during the Persian Gulf crisis and find the distribution differs significantly from that recovered using standard techniques.

Foreign holdings of U.S. Treasuries and U.S. Treasury yields

Foreign official holdings of U.S. Treasuries increased from

On Returns Differentials

400 billion in January 1994 to about

The Performance of International Equity Portfolios

3 trillion in June 2010. Most of this growth is accounted for by a handful of emerging market economies that have been running large current account surpluses. These countries are channeling their savings through the official sector, which is then acquiring foreign exchange reserves. Any shift in policy to reduce their current account surpluses or dampen the rate of reserves accumulation would likely slow the pace of foreign official purchases of U.S. Treasuries. Would such a slowing of foreign official purchases of Treasury notes and bonds affect long-term Treasury yields? Most likely yes, and the effects appear to be large. By our estimates, if foreign official inflows into U.S. Treasuries were to decrease in a given month by

Measuring U.S. International Relative Prices: A Warp View of the World

100 billion, 5-year Treasury rates would rise by about 40-60 basis points in the short run. But once we allow foreign private investors to react to the yield change induced by the shock to foreign official inflows, the long-run effect is about 20 basis points.

The Role of Fiscal Policy in an Incomplete Markets Framework

Estimates of U.S. returns differentials have ranged from exorbitant to quite small, in part because of their volatility coupled with the relatively short time series available. We shed light on underlying drivers of returns differentials by presenting a number of decompositions: a by-asset-class decomposition into yields and capital gains, the Gourinchas and Rey (2007a) composition and return effects, and further decompositions of capital gains that focus on exchange rate effects. While each decomposition informs thinking about returns differentials, one constant is evident throughout: to date the existing differential favoring the U.S. has owed primarily to one factor, a differential in direct investment yields. We discuss how our analysis informs the income puzzle (of positive net income flows to the U.S. even as its net international investment position is negative and substantial) and the position puzzle (of a sizeable gap between the reported U.S. net international position and cumulated current account deficits), provide an initial assessment of the literature on the dynamics of returns differentials, and present a framework to guide a forward-looking view of how returns differentials might evolve in the future.

Measures of International Relative Prices for China and the USA

This paper evaluates the ability of U.S. investors to allocate their foreign equity portfolios across 44 countries over a 25-year period. We find that U.S. portfolios achieved a significantly higher Sharpe ratio than foreign benchmarks, especially since 1990. We test whether this strong performance owed to trading expertise or longer-term allocation expertise. The evidence is overwhelmingly against trading expertise. While U.S. investors did abstain from momentum trading and instead sold past winners, we find no evidence that these past winners subsequently underperformed. In addition, conditional performance measures, which directly test reallocating into (out of) markets that subsequently outperformed (underperformed), suggest no significant trading expertise. In contrast, we offer strong evidence of longer-term allocation expertise: If we fix portfolio weights at the end of 1989 and do not allow reallocations, we still find superior performance in the recent period.

Measurement Matters for Modeling U.S. Import Prices

In this paper we construct a new measure of U.S. prices relative to those of its trading partners and use it to reexamine the behavior of U.S. net exports. Our measure differs from existing measures of the dollars real effective exchange rate (REER) in that it explicitly incorporates both the difference in price levels between the United States and developing economies and the growing importance of these developing economies in world trade. Unlike existing REERs, our measure shows that relative U.S. prices have increased significantly over the past 15 years. In terms of simple correlations, the relationship between our measure of relative prices and U.S. net exports is much more coherent than that between existing REERs and net exports. To explore this relationship further, we use our measure to construct an index of foreign prices relevant for U.S. export volumes and reexamine several export equations. We find that export equations with the new index dominate those with previous measures in terms of in-sample fit, out-of-sample fit, and parameter constancy. In addition, we find that with the new index of foreign prices the estimated elasticity of U.S. exports with respect to foreign income is a good bit higher than the unitary elasticity found in previous studies using other price measures. This has implications for U.S. current account adjustment.

U.S. International Equity Investment and Past and Prospective Returns

A general-equilibrium model is developed to highlight the link between neo-Keynesian models of unemployment and recent results on the constrained sub-optimality of competitive economies with incomplete asset markets. Although the model deviates from the Arrow-Debreu paradigm only by the absence of some contingent claims, the competitive equilibrium exhibits under-employment and balanced-budget fiscal policies have Keynesian effects which are Pareto improving.

Current Account Sustainability and Relative Reliability

In this paper we assemble a measure of international relative prices to gauge the average amount by which prices in China and the USA differ from the prices of their trading partners. Our estimated weighted average of relative prices for China and the USA are the first to use the significantly revised purchasing power parities embodied in the price data from the World Banks World Development Indicators. Our analysis reveals several findings of interest. First, interactions between the structure of trade and the levels of relative prices are sufficiently important to induce divergences between the weighted average of relative prices and conventional real effective exchange-rate indexes. Second, revisions embodied in World Development Indicators price data generally lower the estimate of US international relative prices. Third, net exports are inversely related to the estimate of US international relative price, but, for China, the correlation is positive. Estimating this correlation for other countries reveals no systematic pattern related to the level of development alone. Fourth, unlike previous work, using our price measures we find that an increase in US prices relative to Chinese prices raises the share of Chinas exports to the USA. Finally, there is a distinct possibility of eliminating the long-standing differential in income elasticities of US trade in empirical applications.