A stablecoin is a token redeemable for a dollar. What makes the redemption credible is the reserve: the issuer's holdings of dollars and dollar-denominated paper against the tokens outstanding.
The GENIUS Act, signed 18 July 2025, lists the permitted reserve assets and requires at least one-to-one backing. Tether reported 183.6 billion dollars of USDT in circulation at 30 June 2026 against 187.75 billion of assets, with "the majority" in U.S. government-backed instruments, and a 1.5 billion dollar quarterly profit earned mostly on that paper.
The reserve is why a stablecoin holder in Lagos is, by construction, a lender to the United States Treasury.