Does the deteriorating U.S. investment position reflect borrowing or stock valuations?
Core argument: The U.S. net international investment position swung from -20% of GDP in 2010 to -53% just before the pandemic and -89% as of 2025Q3, almost all reflecting valuation gains on U.S. stocks relative to foreign stock markets.
Foreigners are accumulating more financial claims on Americans than Americans are accumulating on foreigners across every single category: FDI, stocks, bonds, physical currency, deposits, and loans. Foreign official investors supposedly have been mild sellers of U.S. assets over the past 12 months, but the standard measure does not include state-affiliated institutions that operate on behalf of foreign governments. Meanwhile, the U.S. net international investment position has swung massively over the past few years, from -20% of U.S. GDP in 2010, to -53% of U.S. GDP on the eve of the pandemic to -89% as of the end of 2025Q3. Almost all of that reflects massive valuation gains on U.S. stocks relative to stock markets in the rest of the world. The good news is that actual U.S. indebtedness has not meaningfully increased, and the methods used to assign market values to FDI in the U.S. and abroad make the situation look more extreme than it is. (U.S. FDI assets in Ireland are overwhelmingly big tech and big pharma, for example, but the market value of those assets is imputed based on the performance of the maker of Kerrygold.) The bad news is that, if the current level of the NIIP is unsustainable, the easiest way for it to revert is for U.S. stock prices to fall dramatically.

