ARK Invest CEO Cathie Wood says investors tracking the next shift in technology should stop watching only developers and start watching AI agents — the software that will soon spend money on users' behalf.

"We're probably going to be talking more and more about 'follow the agents,'" Wood said during a panel at Robinhood's Summit in Houston on Wednesday. Her comment came near the end of a wider discussion on AI, private markets and technology investing, but it crystallizes a question now confronting both investors and the largest payments and technology companies: what financial infrastructure do machines use when they transact?

For years, Wood has urged investors to "follow the developers" as a signal of where technology is heading, on the logic that engineers gravitate toward useful tools. AI agents — software that carries out tasks on a person's behalf rather than answering questions or generating text — could become an analogous demand signal. If millions of agents begin choosing their own software, services and networks, their activity offers a real-time read on where value is flowing.

Those agents will also need a way to pay. That is where the market-structure fight begins.

Joseph Chalom, co-CEO of SharpLink and former head of digital assets at BlackRock, argued in a post last month that agentic finance must not concentrate in a small number of banks or technology companies. "A world full of intelligent agents means nothing if a handful of companies decide where your money can go," Chalom wrote in the final installment of a three-part series on agentic finance.

The issue, in Chalom's view, is not whether an agent can spend money but how much authority a user grants it and who controls the underlying financial system. A person might authorize an agent to spend up to $500 booking a hotel without granting unlimited access to a bank account. The user should also be able to revoke that authority and inspect a full record of the agent's actions.

Chalom also argued for portability: people should be able to move their agents between financial providers rather than being locked into one company's system. An agent should carry its identity, financial information and permissions to a new provider in much the same way a consumer transfers a phone number between carriers. That, he said, is where open blockchains such as Ethereum have a role.

BlackRock drew the same connection in a September paper examining the overlap between AI and digital assets. The asset manager argued that AI agents could generate new demand for payment systems built for machines — an agent paying for an API call, buying data from another service, or renting computing power without waiting for a human to approve each transaction. Stablecoins and blockchains could handle those payments, BlackRock said, because stablecoins settle around the clock and blockchain-based protocols let software send small payments directly to other software.

The infrastructure is already emerging. Coinbase's x402 protocol is designed to let machines pay for online services such as data or API access. On X, Coinbase CEO Brian Armstrong said "Grok is the leading client for agentic traders on Coinbase currently," though he provided no figures or details on the volume of that activity.

Crypto will not have the market to itself. Stripe, Visa, Google and OpenAI are all building ways for agents to make purchases, and BlackRock's paper noted that traditional payment systems will remain important. The outcome of that competition — open networks versus a concentrated set of banks, payment providers and technology platforms — will determine how much of agentic commerce actually settles on-chain.

For crypto investors, Wood's framing adds a measurable dimension. If AI agents become major economic actors, watching where they transact offers a concrete test of whether stablecoins and blockchains are achieving real-world usage or whether agent payments stay on legacy rails. The on-chain activity of agents — not whitepapers or token announcements — becomes the adoption metric to watch.

The agentic-payments race is still in its earliest stages, with protocols like x402 live and incumbents like Stripe and Visa building in parallel. Which rails capture the first wave of machine-to-machine spending is likely to become clear over the coming quarters.