Debt ceiling concerns drive investors to one-month bills, threaten McCarthy's authority.

Investors are avoiding US Treasury bills that come due in July or August due to concerns that the Treasury Department could hit its debt limit in the coming months. However, they are seeking safe places to park cash, leading to a surge in demand for one-month bills and a drop in yields. The spread between one-month and three-month bills has expanded to its widest level since the one-month bills were introduced in 2001. The Treasury is expected to increase bill issuance once the debt ceiling is raised.