One of the world’s largest banks just proved it can play by its own rules on Ethereum, without breaking anyone else’s.

UBS and Nethermind, a core Ethereum client developer, announced the successful completion of two joint proofs of concept showing that public Ethereum infrastructure can meet the operational and compliance requirements of regulated financial institutions. The tests were conducted on Ethereum’s Sepolia testnet, meaning no real money changed hands, but the implications are anything but theoretical.

What they actually built

The two PoCs tackled different but complementary problems that banks face when they consider touching public blockchains.

The first proof of concept focused on implementing customizable compliance and risk controls at the node level. In English: UBS tested whether a bank could configure its own Ethereum node to only interact with pre-approved addresses and block certain smart contract interactions.

The second PoC addressed transaction routing. It created a system for sending approved transaction bundles through relays to designated block builders, ensuring those transactions get reliably included in blocks. The critical design constraint here was that neither of these controls could alter the open and neutral nature of the Ethereum protocol itself.

Andreas Kubli, UBS’s Group Head of Digital Assets, framed the work as part of the bank’s broader push into tokenized and digital assets.

“Client-led and responsible approach.”

Tomasz Kurowski, head of enterprise business at Nethermind, described the deliverable as “enterprise-grade Ethereum infrastructure” designed to align with regulated market requirements.

Why a $6.9 trillion asset manager cares about testnets

UBS manages approximately $6.9 trillion in invested assets as of Q1 2026. When a firm of that scale runs compliance experiments on Ethereum, it’s not idle curiosity.

This isn’t UBS’s first time testing blockchain waters. In September 2025, the bank participated in a cross-bank payments proof of concept involving deposit tokens, conducted alongside PostFinance and Sygnum under the Swiss Bankers Association. That earlier experiment focused on payments. These latest PoCs go deeper, tackling the infrastructure layer itself.

Nethermind’s involvement adds technical credibility. As one of the teams maintaining a core Ethereum execution client, they understand the protocol’s internals better than almost anyone. Having them architect the compliance layer means it was designed by people who know exactly where Ethereum’s boundaries are and how to work within them without creating fragmentation or compatibility issues.

What this means for investors

UBS and Nethermind demonstrated that compliance controls can be layered on top of public Ethereum at the node level without requiring protocol changes. If one of the world’s largest banks can do it on Sepolia today, the blueprint exists for dozens of institutions to replicate it on mainnet tomorrow.

UBS has indicated it plans to advance this technology as regulations evolve. Investors watching this space should pay less attention to when the next testnet experiment happens and more attention to when the first mainnet deployment goes live.