I document the profits on a trade that is long the old 30-year Treasury bond and short the new 30-year Treasury bond, and is rolled over every auction cycle from June 1995 to November 1999. Despite the systematic convergence of the spread over the auction cycle, the average profits are close to zero. The difference in repo-market financing rates between the two bonds is a significant cost of carry in this trade. I show that variation in the bond/old-bond spread is driven by the Treasury supply of 30-year bonds as well as aggregate factors affecting investors’ preference for liquid assets.

We present a theory in which the key driver of short-term debt issued by the financial sector is the portfolio demand for safe and liquid assets by the nonfinancial sector. This demand drives a premium on safe and liquid assets that the financial sector exploits by owning risky and illiquid assets and writing safe and liquid claims against them. The central prediction of the theory is that safe and liquid government debt should crowd out financial sector lending financed by short-term debt. We verify this prediction with US data from 1875 to 2014. We take a series of approaches to rule out standard crowding out via real interest rates and to address potential endogeneity concerns.