Pierre-Olivier Gourinchas guesses that last week the U.S.'s net foreign asset position improved by $400 billion. Americans' assets overseas, you see, are primarily denominated in local currencies or are real assets. Foreigners' assets here, you see, are primarily denominated in dollars. The weakening of the dollar thus raised Americans' assets minus liabilities by about $400 billion.
Nice work if you can get it. Exorbitant privilege.