Stablecoin issuers have become a real force in the market for US Treasury bills, but their buying power stops dead at the short end of the curve. GENIUS Act reserve rules effectively cap eligible reserve assets at 93 days of maturity, which means every marginal dollar minted into USDT, USDC or their competitors flows into T-bills and cash equivalents — not into the long-dated bonds where the Treasury’s real funding problem lives. The result is a stablecoin complex that is structurally useful to Washington and structurally irrelevant to its hardest liability.
What the Reserve Rules Actually Permit
The GENIUS Act framework was written with redemption risk in mind. Issuers must back tokens with high-quality liquid assets that can be liquidated quickly if holders run for the exits, and that logic lands issuers almost exclusively in T-bills, overnight repo and insured deposits. Assets with 93 days or less to maturity qualify cleanly; anything longer introduces duration risk that a payment token cannot carry. The tradeoff is deliberate. You get a reserve base that survives a redemption wave, at the cost of permanently excluding stablecoins as a buyer of 10-year and 30-year paper.
T-Bill Demand Is Real — and Growing
With combined stablecoin supply in the hundreds of billions, issuers collectively rank among the larger holders of short-dated Treasuries, comparable to money market funds in their bill appetite. Every net inflow into stablecoins — and we noted last week that supply has turned positive again after three months of contraction — translates directly into incremental bill demand at auction. For the Treasury’s short-term funding needs, this is a cheap and reliable bid. It lowers the government’s cost of rolling bills and deepens the most liquid part of the curve. That part of the story is genuinely favorable, and it is the part policymakers like to cite when they defend stablecoin legislation.
The $28 Billion Long-Bond Problem Stays Unsolved
The uncomfortable part is the maturity mismatch. The Treasury’s challenge is not rolling bills — it is finding durable demand for long-dated bonds amid heavy issuance, and an estimated $28 billion problem in that segment, as CryptoSlate frames it. Stablecoins cannot help here by design: the 93-day cap excludes direct long-bond purchases, and even indirect exposure through ETFs or derivative structures sits outside the reserve perimeter regulators have drawn. A fully-reserved payment token that bought duration would be taking exactly the risk GENIUS Act rules exist to prevent. So the industry’s growth solves a problem the Treasury does not really have, while leaving the one it does have to traditional buyers — funds, foreign central banks, households.
What to Watch
The variable to track is the spread between bill yields and the rest of the curve. If stablecoin supply keeps growing, bill demand tightens further, which can compress front-end yields and steepen the curve — a subtle subsidy to short-term borrowing paid, effectively, by stablecoin users and issuers. Watch also whether Congress or the Treasury explores mechanisms to channel some stablecoin demand into longer maturities, such as approved duration-limited bond funds or term repo facilities. None exist today, and creating them would reopen the exact reserve-safety debate the GENIUS Act settled. For now, stablecoins are a T-bill instrument, and the long-bond market should not expect help.