Why did the dollar rally while foreign capital flowed out?
Core argument: Foreign capital flowed out of U.S. markets in late 2008, contradicting the assumption that the dollar's rally during the global financial crisis reflected foreign investors moving funds into the United States.
Because the dollar (somewhat surprisingly) rallied during the crisis [i.e. the GFC], there is an assumption that foreign investors moved funds into the U.S. That isn’t quite true. Capital from abroad flowed out of the U.S. market in late 2008. The disaggregated chart tells a clear story of reduced foreign demand for U.S. assets amid the crisis. [This is what ] produced the bid for dollar assets. U.S. money market mutual funds that had lent to foreign (mostly European) banks wanted their money back, [as did] American banks that had lent out dollars to carry traders betting on the continued decline of the dollar relative to emerging economies. Put differently, the dollar was one of the funding currencies for a host of carry trades prior to the global financial crisis, as the dollar had been in a sustained slump and U.S. rates were relatively low. The dollar, as well as the yen. It is not a coincidence that the yen also rallied during the global financial crisis. That to me is a critical clue. Most attribute the ‘08 yen rally to a carry unwind, rather than a bid for the yen as a “reserve” currency. That could be said for the dollar as well. Investors should not assume that the dollar will rally in future instability.

