USDC holds $73.1B in reserves across cash, T-bills and overnight Treasury repo via BlackRock's money market fund. The BIS warns that at trillion-dollar scale, stablecoin flows could ripple through front-end yields and repo markets.
The Bank for International Settlements put stablecoin reserves on notice. In its 2026 Annual Economic Report, the BIS modeled how a stablecoin market in the one-to-three-trillion-dollar range could push down short-term Treasury yields and add volatility to repo if issuance or redemptions swing quickly. USDC alone has $72.9 billion in circulation. The combined footprint of the top fiat-backed coins already registers in the hundreds of billions.
The plumbing that supports them is the same money market infrastructure that sets short-term rates for everyone.
Stablecoin reserves sit in three buckets: cash at banks, short-dated U.S. Treasuries, and overnight Treasury repurchase agreements. USDC reports $73.1 billion in total reserves as of July 23, 2026, with most assets held in the Circle Reserve Fund, a BlackRock-managed government money market fund that can hold cash, T-bills, and overnight Treasury repo. Circle's transparency page shows that reserve total slightly exceeds circulation, a gap driven by accrued interest income, the company said.
State Street launched its own stablecoin reserve fund, the Stablecoin Reserves Money Market Fund (ticker SSRXX), on June 8, 2026. As of June 30, 2026, SSRXX held about $121 million in net assets, with 95.77% in Treasury repurchase agreements and 4.23% in Treasury debt, according to the fund's sector allocation. That mix prioritizes same-day liquidity, State Street said. The fund is designed so that a stablecoin issuer can meet redemptions without selling T-bills into a falling market.
Overnight Treasury repo is the key bridge. The fund lends out Treasuries and receives cash today, agreeing to reverse the trade the next day. Because the collateral is U.S. government debt and the term is overnight, credit and duration risks stay low. The trade-off is yield. Short and safe pays less than longer and riskier, but the mandate is stability and liquidity first, not returns.
Government money market funds like the Circle Reserve Fund and SSRXX operate under SEC Rule 2a-7, which sets hard limits on credit quality, maturity, and portfolio liquidity. They must hold minimum daily and weekly liquid assets, keep weighted average maturity short, and limit exposure to any single issuer. The 2023 SEC reforms toughened parts of the regime. Government funds are not subject to swing pricing rules that apply to institutional prime funds, which reduces the odds of surprise redemption frictions, the SEC said at the time.
In a heavy redemption day, the reserve manager follows a liquidity waterfall. First, use bank cash. Next, roll or unwind overnight Treasury repos to raise cash without selling bills. If needed, sell some bills or let near-dated maturities pay out and use that cash. Because the portfolio is short, maturities are always coming due within days to weeks. The exception is if something external snarls payment rails or if counterparties step back from repo for a session. That is rare, the BIS flagged it as a potential systemic risk at scale.
The BIS modeling showed that large inflows into stablecoins push more cash into bills and Treasury repo via reserve funds, which can nudge front-end yields lower. Large outflows do the opposite, with funds unwinding repo and selling or letting maturities roll off. Even if managers avoid fire sales, the footprint shows up in money market flows and bank funding costs. The BIS stopped short of calling it a crisis trigger, the report made clear that regulators are watching the stablecoin reserve plumbing as it grows.
For users, start with the headline numbers. Reserve total should meet or slightly exceed circulation. Confirm assets are limited to cash, U.S. Treasuries, and Treasury repo, ideally via a regulated 2a-7 government money market fund. Note the breakdown across those buckets and any concentration in a single bank or counterparty. If the reserve sits in a money market fund, scan the fund's daily or monthly holdings. SSRXX's heavy allocation to Treasury repo signals same-day liquidity for potential redemptions, State Street's disclosures show.
The BIS report is scheduled for full release on June 30, 2026.
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