T-bill yields have jumped as a rush of new supply meets a cooler bid. This week's eight-week auction showed it clearly, pairing record-weak demand with a 4.05% yield, the highest level for that tenor in more than a year. The hesitancy tracks a bill calendar swelling to finance a larger deficit and a murky path for Federal Reserve policy.
Even so, the pressure has not broken into overnight funding, where cash remains plentiful. That keeps money markets stable for now, but also exposed if bill stress grows.
"Several competing forces are shaping money markets this month," Barclays strategist Samuel Earl wrote. "Depending on where one looks, the market appears caught between two very different narratives: signs of emerging funding pressure on one hand, and surprisingly subdued conditions on the other."
Treasury has already added close to $100 billion in net bills in the first half of October, per TreasuryDirect, and Barclays projects new bill supply topping $320 billion in the next six weeks. As that pipeline builds, bill yields have moved higher relative to swap rates tied to the Secured Overnight Financing Rate, a market gauge of risk free borrowing. Yet for much of October, SOFR has sat at or below the Fed's interest on reserve balances rate, a sign that liquidity remains ample despite the bill-market strain.
Money-market funds, the dominant bill buyers, have seen inflows cool even as issuance accelerates. Managers have tilted more defensive, favoring shorter maturities given uncertainty around the Fed's next steps, Earl noted. Taxable money funds' average maturity is down to 35.3 days, 3.4 days shorter in 2024 and 7.7 days below the mid April high, according to Wells Fargo using Crane Data. The pullback was sharpest in Treasury funds, where institutional portfolios cut maturities by nearly 10 days since end April.
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Those shifts have funneled demand toward repo and floating rate paper rather than fixed rate bills. Bank of America strategists say Federal Home Loan Bank issuance has increased as FHLBs refinance maturing obligations and meet bank funding needs, with most of that supply in floating rate notes while other bonds and discount notes have declined.
Repo rates have held firm. Barclays attributes the calm to a fundamental pullback in risk-taking by levered players this year, as opportunities in relative-value and basis strategies have narrowed, which in turn lessens reliance on dealer-provided funding. Dealer repo books have also grown after supplementary leverage ratio constraints were relaxed; Barclays estimates this easing has let G-SIBs lift their combined repo and reverse repo holdings by between $300 billion and $350 billion through September.
The cash cushion and investor appetite for the very shortest maturities have kept overnight funding calm, but that does not erase risk. The Fed may decide to keep pausing its reserve management purchases for longer if funding markets show few signs of strain. The central bank said this week that for the third straight month it will not buy T-bills for those operations. That stance could add to pressure in the bill market and potentially spill into overnight funding. As Earl put it, "Continued slack in funding markets raises the risk that the Fed could remain on hold for longer, particularly if the reduction in balance sheet capacity into year end is more than offset by declining leverage demand."
Short-duration cash strategies are getting even shorter, floating rates are in favor, and bill yields are rising to clear heavier supply while repo stays placid. For portfolios parking cash, watch the bill swap spread, SOFR versus IORB, and the Fed's stance on reserve management purchases. Those are the signposts for where short term returns and liquidity will show up next.
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