The Plumbing: How Money-Market Brittleness Returned in 2026

On 31 December 2024, U.S. banks borrowed a record $74.6 billion through the Federal Reserve’s Standing Repo Facility, eclipsing the prior $50.35 billion intraday print from 31 October. On 15 September 2025, the same backstop was tapped for roughly $18.5 billion in a single operation, its largest non-year-end draw since inception. On 31 December 2025, the facility was again called upon as quarter-end balance-sheet constraints squeezed dealers and the Secured Overnight Financing Rate cleared the Interest on Reserve Balances rate by a margin not seen outside the 2019 episode. None of this resembles 2008. It is a slow, repeated demonstration that the post-2014 plumbing of the world’s largest funding market has lost the cushion that once absorbed quarter-end strain without official intervention. The Fed’s reverse repo drain, the Treasury’s bill-heavy issuance mix, and the constraints binding primary-dealer balance sheets have converged. The 2026 regime is not a crisis. It is a higher steady-state demand for the central bank’s safety valve.

From Cushion to Floor. The Overnight Reverse Repurchase Facility (ON RRP) peaked at $2.55 trillion on 30 December 2022, when money-market funds parked excess cash with the Fed at the administered floor rate. By late 2025, the balance had drained to under $200 billion, and at points across early 2026 it ran in the single-digit billions. The two-and-a-half trillion dollars of yieldless balances that money funds had been holding migrated into Treasury bills, accelerated by the Yellen-era tilt toward short-dated issuance. Bills represented roughly 22 percent of all outstanding marketable Treasury debt at the end of October 2025, up from 13 percent in October 2015, near the 24 percent pandemic peak. The marketable Treasury stock crossed $36 trillion in 2025; Treasury issued roughly $30.2 trillion of marketable securities during fiscal 2025, and expected privately-held net marketable borrowing of $569 billion in Q4 2025 and $578 billion in Q1 2026. The arithmetic is the story: the system retired its largest demand-side shock absorber while supply expanded at multi-decade highs. Friction that the ON RRP previously masked now passes through to overnight rates.

Quarter-End Tells. The diagnostic is the SOFR-IORB spread at reporting dates. Through 2021 and most of 2022, SOFR traded below IORB, evidence of plentiful collateral demand and abundant reserves. Since mid-2024 the spread has drifted positive, and at each subsequent quarter-end has spiked: September 2024, March 2025, September 2025, December 2025, and again at the January 2026 turn. The September 2025 episode is the cleanest evidence. SOFR rose 5 to 8 basis points in the first week of September, the Tri-party General Collateral Rate moved about 10 basis points to roughly 4.50 percent, and on 15 September the SRF cleared $18.5 billion. The December 2025 turn produced renewed SRF activity and a positive SOFR-IORB print persistent enough that the New York Fed publicly highlighted dealer balance-sheet capacity as the binding constraint. These are not the 282 basis-point SOFR move of 17 September 2019, when intraday rates touched 10 percent and the Fed injected $75 billion. They are the controlled telemetry of a system whose volatility is now expected and pre-funded.

The Basis Trade Overhang. The leveraged carry between cash Treasuries and the corresponding futures contract has migrated from a niche relative-value strategy to a structurally significant source of Treasury demand. Cayman-domiciled hedge funds held $1.85 trillion of U.S. Treasuries in late 2025, up roughly $1 trillion from 2022, with associated repo borrowing of $2.5 trillion in Q4 2024, a 104 percent jump in two years. Hedge funds’ share of Treasury cash securities reached 10.3 percent in Q1 2025, surpassing the 9.4 percent pre-pandemic peak. CFTC leveraged-fund net short positions in Treasury futures across maturities up to 10 years exceeded $1 trillion in March 2025. Federal Reserve Governor Lisa Cook flagged the position on 20 November 2025; the Office of Financial Research and NY Fed have both warned that the largest funds operate at leverage exceeding 18 to 1. The basis trade absorbed supply that primary dealers could not, but it absorbed it via repo financing that competes directly with banks and money funds for the same overnight liquidity. The trade is a load-bearing wall and a fault line at once.

Dealer Capacity, Not Reserves. The standard diagnosis treats funding stress as a reserves problem. The 2025 evidence points to the dealer-intermediation layer. Primary-dealer balance sheets, capped by the Supplementary Leverage Ratio, expand mechanically as Treasury supply grows. Each marginal dollar of bills, notes, or repo financing they intermediate consumes regulatory capital at the same rate as a marginal dollar of corporate credit risk. The Fed, FDIC, and OCC published a Notice of Proposed Rulemaking on 25 June 2025 to recalibrate the Enhanced SLR for U.S. global systemically important banks, replacing the gold-plated buffer with one equal to 50 percent of the GSIB capital surcharge. The agencies estimated a less-than-2 percent aggregate reduction in tier-1 holding-company requirements and a roughly 27 percent reduction at depository-institution subsidiaries. The comment window closed on 26 August 2025. The proposal does not exempt Treasuries from the denominator, although alternatives in the release contemplated that step. The expected benefit is incremental: more rope for dealers at quarter-ends, not a structural reset.

Central Clearing Arrives in Stages. The SEC’s December 2023 Treasury clearing rule has been pushed back twice. Current compliance dates require central clearing of eligible cash market transactions by 31 December 2026 and eligible repo transactions by 30 June 2027. Fixed Income Clearing Corporation remained the sole approved Treasury CCP until 1 December 2025, when the SEC approved CME Securities Clearing Inc. as a second clearing agency. ICE Clear Credit has signaled intent to apply. The mandate’s promise is multilateral netting that compresses dealer exposures and frees balance-sheet capacity at the moments it is scarcest. Its execution risk is non-trivial. Margin requirements at central counterparties absorb collateral that previously sat with dealers, the on-ramp for buy-side firms is operationally heavy, and a multi-CCP market introduces cross-margining frictions that have not been stress-tested under live conditions. The transition window through 2026 and into 2027 overlaps precisely with the period in which the Fed must manage the end of balance-sheet runoff without provoking a 2019-style accident.

The Fed’s Two-Step. The FOMC announced on 29 October 2025 that quantitative tightening would end on 1 December 2025, after $2.4 trillion of runoff. The December meeting set out roughly $40 billion per month of bill purchases through mid-April 2026 as a reserve-management operation, with that pace then “significantly reduced.” Reserves stood near 13 percent of GDP heading into 2026, against an internal Fed soft target of 10 to 11 percent. The pivot was earlier than the September 2019 precedent would have justified on the surface, which is the point: the Fed read the SRF utilisation, the SOFR-IORB drift, and the persistent quarter-end strain as evidence that the ample-reserves regime was approaching its lower edge. The balance sheet will now grow with trend reserve demand rather than shrink. The political cost of the pivot has been minimal because the operation looks like plumbing, not policy.

The Verdict. The 2026 money-market regime is not the 2019 regime with worse parameters. It is a different system. The administered floor that absorbed two-and-a-half trillion dollars of money-fund cash is gone. The supply pipeline running through primary dealers is structurally larger, structurally shorter-dated, and structurally more leveraged via the hedge-fund basis trade. The two policy responses, eSLR recalibration and central clearing, are transitions whose payoff sits in 2027 and beyond. In the meantime, the SRF is the load-bearing element, and its record prints are no longer anomalies but the new instrumentation. Markets that intermediate $36 trillion of debt cannot run frictionlessly on the same balance-sheet apparatus that intermediated $20 trillion a decade earlier. The Fed has implicitly conceded the point by ending runoff; the question that remains is whether ample reserves can be preserved without permanent, scheduled, large-scale Treasury purchases, which is to say whether the operational floor and the political fiction of a passive central bank can coexist for another cycle.

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