The entire machine-payment ecosystem now runs almost entirely on a single stablecoin. More than 98% of all settlements made by AI agents in the past year were processed in Circle’s USDC , according to a new report from crypto investment firm Keyrock — a concentration that researchers say carries risks the industry has largely ignored. One Stablecoin To Rule Them All Keyrock researcher Ben Harvey, writing in collaboration with Coinbase and blockchain firm Tempo, said the dependence on one issuer’s infrastructure, regulatory standing, and reserve management creates a systemic exposure that nobody in the space is publicly discussing. A regulatory challenge against Circle, a de-peg event, or even a prolonged outage would leave the agent economy with no alternative settlement option. Harvey said that risk warrants serious attention as transaction volumes continue to grow. In one year, machine payments have evolved from concept to live ecosystem, with agents settling 176M transactions. Our research with @CoinbaseDev , @tempo , and featuring @virtuals_io analyses the payment stack’s evolution, how the economics work, and what stands in the way. pic.twitter.com/W6DGGYAUC0 — Keyrock (@keyrock) May 21, 2026 The numbers behind the report are striking. From May 2025 through April 2026, AI agents settled over $70 million across 176 million transactions — an average deal size of about 31 cents. That figure alone explains why traditional payment networks were never going to work here. A standard processing fee of roughly 30 cents per transaction makes anything below a dollar completely unworkable on rails built for consumer credit cards. An agent paying three cents to call a weather API cannot route through Visa. Why Traditional Rails Were Left Behind Stablecoins filled that gap not because they were chosen but because nothing else could do the job. The economics of legacy payment infrastructure simply collapse at sub-dollar volumes, and crypto rails carry no fixed per-transaction fee that would eat the entire value of a microtransaction. By the end of the first quarter of 2026, more than 104,000 agents had been registered across 15 or more directories and registries worldwide. Harvey described the shift as going from concept to a developed ecosystem in just 12 months. Incumbents appear to have taken notice — the report says more than $8 billion has been deployed in acquisitions by established players looking to stake a position in what is emerging as a new payment stack built around autonomous software rather than human users. A Market Built On One Foundation AI agents are already being used to build Web3 applications, launch tokens, trade, and interact autonomously with protocols and services. A CoinGecko survey of 2,632 crypto users conducted last April found 87% were willing to let AI agents manage at least 10% of their crypto portfolio. Circle CEO Jeremy Allaire has predicted that billions of agents will operate with stablecoins on users’ behalf within five years. Featured image from Unsplash, chart from TradingView
