From a much longer IMF profile of Hélène Rey, professor of economics at the London Business School:
... Among her most influential work is the research she did with Gourinchas when she was at Princeton on the role of the United States in a globalized financial system. Blanchard says it “changed the discussion on the current account deficit in the United States.”
Before the recent global financial crisis, when economists and politicians were concerned about the ballooning U.S. current account deficit, Gourinchas and Rey showed that the U.S. position was not as bad as it looked because of the country’s role as the center of the international financial system.
“Although the U.S. was running a big trade deficit, economists were not taking into account the large amounts the U.S. was earning on the financial side from capital gains and changes in the value of the dollar,” Gourinchas told F&D.
“For example, almost all U.S. foreign liabilities are in dollars, whereas approximately 70 percent of U.S. foreign assets are in other currencies. So a 10 percent depreciation of the dollar increases the value of foreign assets and represents a transfer of about 5.9 percent of U.S. GDP from the rest of the world to the United States. For comparison, the trade deficit on goods and services in 2004 was 5.3 percent of GDP. So these capital gains can be very large.”
As Gourinchas and Rey (2005) pointed out, a depreciation of the U.S. dollar has two beneficial effects on the external position of the United States. It helps boost net exports and increases the dollar value of U.S. assets.
Gourinchas and Rey said that the U.S. position at the center of the system gave it what they called an “exorbitant privilege”... The exorbitant privilege, Rey and Gourinchas explained, came about because the United States could borrow at a discount on world financial markets and get high yields on its external assets. They tracked how the United States had gradually taken on riskier overseas investments.
“Then we pushed these ideas further, by pointing out that the key role of the United States makes it also look very much like an insurer for the rest of the world,” Rey explains. ...
Gourinchas said Washington has become more like the world’s venture capitalist since the 1990s. “During the whole period, U.S. assets have shifted more and more out of long-term bank loans toward foreign direct investment (FDI) and, since the 1990s, toward FDI and equity. At the same time, its liabilities have remained dominated by bank loans, trade credit, and debt—that is, low-yield safe assets.
“Hence, the U.S. balance sheet resembled increasingly one of a venture capitalist with high-return risky investments on the asset side. Furthermore, its leverage ratio has increased sizably over time.”
Rey says they expanded on this research during the global financial crisis, finding that the United States had reversed its role by channeling resources to the rest of the world through its external portfolio—on a large scale. “Our estimate is 13 to 14 percent of U.S. GDP in 2008 alone. So that was very significant.”
The United States was providing “some sort of global insurance to the world economy and the rest of the world—earning the equivalent of an insurance premium in good times and paying out in bad times. And that’s exactly what we see in the data.”
“While the United States enjoys an exorbitant privilege on one side,” says Rey, “it also, as global insurer, has an exorbitant duty in time of crisis on the other.”