Scenario description
Assume the late-September 2026 long-end Treasury repricing leads to an operational US debt-management response before the resolution date. The initiating change is that the US Treasury, in response to persistent long-end yield pressure, heavy duration supply, or liquidity concerns, puts into effect a materially enlarged long-end buyback operation, changes auction or issuance composition to reduce long-duration supply relative to previously published plans, or begins another concrete Treasury-market-functioning measure. The reported starting point is a 10-year yield as high as 5.304%, a 30-year yield around 5.62%–5.64%, and a roughly 85–87 basis-point quarterly rise in the 10-year; any additional duration or yield stress used to justify the response is hypothetical unless confirmed by later sources. Unknown exact buyback sizes, auction reductions, and maturity-specific changes remain explicit rather than assumed.