Stablecoins now settle trillions of dollars a year — volumes in the range of the major card networks — with a combined supply above a quarter of a trillion dollars, almost all of it USD-denominated. Functionally, they are offshore dollar accounts with instant, programmable settlement.
Two design families dominate. Reserve-backed coins (USDT, USDC) hold treasury bills and repo against issued tokens — making their issuers, in aggregate, one of the largest holders of US Treasury bills in the world. The issuers' business model is simply the interest on those reserves, which is why stablecoins became one of the most profitable business models per employee in financial history.
The infrastructure consequence is underrated: a stablecoin transfer is a full settlement — no correspondent chain, no cut-off times, no T+1. For cross-border payments, emerging-market savings and machine-to-machine (AI agent) payments, stablecoins are becoming the default rail, with regulation (MiCA in the EU, the GENIUS Act in the US) converting them from grey zone to licensed instrument.
For a data layer, stablecoins are also the most transparent money in existence: supply, flows and holder distribution are on-chain, queryable in real time — a preview of what all financial reference data could look like.