For decades, U.S. Treasury securities commanded a pricing premium that economists call the convenience yield — the extra return investors were willing to forgo in exchange for holding the world’s most liquid, safest, most universally accepted collateral. That premium is eroding. The GAO’s March 2026 federal debt management report (GAO-26-107529) treats this as a structural shift, not a market fluctuation, and the data support that reading. The convenience yield is not directly observable.

The debt limit is, in strict operational terms, a fiction. Congress authorizes spending through the appropriations process. It authorizes revenue through the tax code. The debt that results from the gap between those two is mathematically determined. The debt limit then arrives as a third act — a separate legislative mechanism that can block Treasury from issuing the securities needed to pay obligations Congress has already created. It does not constrain spending.