Same Firms, Every Layer: Who Operates Agentic Payment Infrastructure
The Linkmerica Research Team · Research note · October 1, 2026
The finding
The infrastructure that lets AI agents pay is being built in layers: payment protocols that authorise agent transactions, blockchains that settle them, an open standard that carries payment requests over the web, an industry coalition drafting guidance for all of it, and the stablecoin much of it settles in. Each layer is presented as distinct.
Mapping who holds a role at each layer, using the organisations' own published lists, shows the same small group of firms at almost every one. Visa holds a role at five of the six layers mapped here. Circle holds five. Mastercard holds four. Standard Chartered appears on both institutional blockchains, directly on one and through a majority-owned custodian on the other.
The map
| Layer | Visa | Mastercard | Circle | Standard Chartered |
|---|---|---|---|---|
| Operates an agent payment protocol | TAP | AP4M | — | — |
| Arc validator | Yes | Yes | Yes, and operator | Yes |
| Tempo validator | Yes, anchor | — | — | Via Zodia Custody |
| x402 Foundation premier member | Yes | Yes | Yes | — |
| Agentic Payments Alliance founder | Yes | Yes | Yes | — |
| Issues the settlement asset | — | — | USDC | — |
What each role is
Protocols. Visa operates Trusted Agent Protocol, in which Visa maintains the directory of agent public keys. Mastercard operates Agent Pay for Machines. Linkmerica scored both under its Agentic Custody Readiness framework in July: TAP at 7.2 and AP4M at 6.6, both HIGH. The scale is inverted; a higher score means higher risk.
Arc. Circle's Layer-1, now live, is "operated by a permissioned validator set of known operators." Its founding validator cohort is BlackRock, Circle, Galaxy, Figment, Mastercard, NYSE, Standard Chartered, Sumitomo Corporation, Visa and Worldpay, now part of Global Payments. Arc states that the ability to transact on the network depends on obtaining and using USDC to pay gas fees.
Tempo. The Stripe-incubated Layer-1 announced Visa, Stripe and Zodia Custody as its first external validators in April 2026. Visa states its node is configured and managed in-house. Zodia Custody is majority-owned by Standard Chartered.
x402. The open standard for payments over HTTP moved to Linux Foundation governance, with operational launch on July 14, 2026. Its seventeen premier members include Visa, Mastercard and Circle. Circle's announcement quote came from the Vice President of its Arc Platform.
The Agentic Payments Alliance. Launched in August 2026 with twenty-six founding members including Visa, Mastercard and Circle. Its stated focus areas include agent authorization and identity standards.
Why this matters for custody risk
None of this is improper. Experienced operators bring reliability and regulatory credibility, and concentration among a few capable firms is common in early infrastructure.
The question for a risk assessor is narrower. When one firm operates a payment protocol, validates the chains that settle it, helps govern the standard that carries it, and sits in the coalition defining its controls, those layers are not independent failure domains. An operational incident, a policy decision or a sanctions action at that firm can reach several layers at once. An institution that believes it has diversified across different rails may have diversified less than it appears.
Circle's position is the clearest case. It issues USDC, operates Arc, validates Arc, and USDC is mandatory for Arc's gas. The settlement asset, the network and its fee token share an issuer.
There is also an independence question. The firms helping write standards for agent authorization are the firms operating the infrastructure those standards would assess. That is the same structural issue Linkmerica has raised about payment-rail operators evaluating their own protocols, one layer up.
Limits
Roles are as published on the dates checked; validator sets and memberships change, and founding cohorts may since have expanded. A role is not control: the Arc and Tempo validator sets each include several operators, and x402 governance has around forty members. This note does not assess the security of any network. Claims that could not be confirmed from the organisations' own publications are excluded, including a reported additional Arc validator and promotional testimonials on Arc's homepage, where the same quotation is attributed to two different firms.
Disclosure
Linkmerica rates Visa TAP and Mastercard AP4M. It has no commercial relationship with any firm named here and accepts no payment from rated entities.
Sources
- Arc founding validators, gas requirement and Arc Portal: arc.io, accessed 2026-10-01
- x402 Foundation premier members: x402.org, Linux Foundation operational-launch announcement, July 14, 2026
- Tempo validators: Visa announcement, April 2026, as reported by Finextra and CoinDesk
- Agentic Payments Alliance founding members: Rain announcement via PR Newswire, August 2026
- Visa TAP and Mastercard AP4M scores: linkmerica.com/protocols/visa-tap/ and /protocols/ap4m/
Linkmerica is a trade name of CASPO LLC. Research is for informational purposes only and does not constitute financial or investment advice. Based on publicly available information as of October 1, 2026.