A $2 trillion deficit does not need a default to break markets. Current estimates put both federal deficits and privately held net marketable borrowing near $2 trillion annually through FY2028. That supply can still clear cleanly—30-year auction bid-to-cover ratios remain near 2.5—but auction-day yield moves have become larger. The buyer base is getting faster In 2007, foreign official institutions, the Fed and banks—the relatively price-insensitive bloc—held roughly 75% of Treasuries; today that share is 52%. The gap is increasingly filled by capital that needs the price, spread and funding terms to work every day. Large hedge funds’ Treasury holdings rose from 4.5% to 8.5% of privately held Treasuries between early 2023 and September 2025, while gross Treasury exposure doubled to $4 trillion. By September 2025, their repo cash borrowing had reached $3 trillion, with the 50 largest funds accounting for roughly 90% of gross exposure. Much of this is not a bearish macro bet. It is relative-value arbitrage: own the cash bond, short the future, lever a thin spread. The safe asset is financed unsafely Repo makes that trade scalable, but it also makes it conditional. A small group of dealers provides most of the funding, while roughly 70% of bilateral dollar repos with hedge funds carry zero haircuts. That works beautifully until dealer balance sheets tighten, margins rise or volatility moves the basis against the trade. Then the trade reverses: repo gets expensive, funds sell Treasuries, yields rise, marks deteriorate and margin pressure forces more selling. A version of that loop surfaced in March 2020, when even the Treasury market needed central-bank support. No failed auction or default is required. Why stocks should care For stocks, the first-order hit is lower multiples; the second-order hit is tighter credit, thinner dealer capacity and weaker growth. The Fed may again have little choice but to restore market function, but bond purchases aimed at fixing liquidity can look uncomfortably similar to financing a Treasury issuing $2 trillion a year. That is where market plumbing becomes fiscal-dominance risk. Bottom line: America’s fiscal risk may surface first as a leverage and liquidity event, not a solvency event—and markets built on short-term funding usually look strongest just before that distinction stops mattering.