EXCLUSIVE: "What We Build and What We Buy" - Biswarup Chatterjee, Citi Services in 'The Paytech Magazine'

If you’re selling your latest altfi idea into a major bank, it’s as well to know what the boundaries are

Banks have argued over build-or-buy for as long as there have been fintechs to buy from, and digital assets have succeeded in throwing up a whole host of new considerations.

A bank can buy in a stablecoin on-ramp, a blockchain connector or a wallet. But the compliance obligations that come with moving money on those rails tend to stay with the bank, whoever wrote the code, says Biswarup Chatterjee, who runs Partnerships and Innovation at Citi Services.

That bank division is also responsible for new products and new business development, which makes Chatterjee the person most fintechs engage with when looking to work with Citi.

“Operational, design and technology choices are the firm’s decision [depending on] what we get from a fintech,” says Chatterjee. “But when it comes to compliance risk, AML risk and complying with the Bank Secrecy Act, that’s completely on the bank. That’s why most of our clients bring business to Citi or any other regulated institution: they want that trust and that capability, and it’s also what our regulators expect.

“So yes, fintechs may help us on the technology side. But the risk, the AML, the obligations around safety and soundness, that’s completely on us.

“Traditional or blockchain, the client relationship is always with Citi.” 

Chatterjee has an idiom for the buy-or-build question. “I call it, ‘BoB’,” he says. But the answer is never his alone. “We make the decision together with the business, based on the client’s needs, and with our technology teams,” he says

 And BoB, it turns out, has rules.

“When we’re exploring a new market, when we need speed to get into a certain area, or when the use case is still nascent but a small number of customers are asking for it, we’ll typically go towards a partnership model,” says Chatterjee. “There are times when we’re working with partners and creating critical intellectual property together. That’s where we’ll also invest in them from an equity capital perspective, so we can guide them, help them and shape that intellectual property with them. For scalable, large-volume, high-client-impact use cases, we will always build it ourselves.”

In October 2025, for example, Citi Ventures invested in BVNK, the London-based stablecoin infrastructure provider whose clients include Worldpay, Flywire and dLocal. The clearest recent case of partnership winning out under BoB is Coinbase. The two firms first said in 2025 that they would explore stablecoin payout options for Citi’s institutional clients.

In September this year, they expanded the arrangement in two directions, launching first in the US. Coinbase has picked Citi’s Virtual Account Wallet, a banking-as-a-service product, to give its payments customers bank-account-style functionality, with incoming fiat automatically converted into stablecoins.

In the other direction, Citi’s institutional clients will be able to accept stablecoins at checkout through Spring by Citi, its e-commerce payments platform, with Coinbase Payments handling the digital side, converting the coins to fiat, with Citi settling the cash.

“That was clearly a case where partnership won,” says Chatterjee. “We worked with Coinbase, an external provider with much better expertise and knowledge of that market than us.”

The division of labour was visible in the announcement by Alec Lovett, Coinbase’s Head of Infrastructure Product, that Coinbase was ‘powering its Virtual Accounts with Citi’s regulated banking infrastructure’. Coinbase brings the stablecoin know-how. Citi brings the bank, and its regulatory purview.

BoB isn’t always an easy choice. Asked what he wishes Citi had built instead of buying, Chatterjee chooses data capability.

“In hindsight, looking at the AI revolution coming into financial services, much more structured and standardised data sets, not just within Citi but across the industry, is something I think we should really have spent much more time building,” he says.

RESULTS NOT RAILS

What may come as a painful blow to engineers, is how little a service’s underlying technology matters to the client paying for it. That became apparent to Chatterjee while rolling out Citi Token Services and the bank’s other blockchain products. Citi Token Services moves tokenised deposits over a private permissioned blockchain, giving corporate clients 24/7 liquidity movements across Citi’s network.

In September 2026, the bank added Japan and the UAE, taking it to seven markets alongside the US, UK, Ireland, Singapore and Hong Kong.

“We’ve seen that clients really care about the service, the benefit they get and the experience,” says Chatterjee. “Very few of them really care what technology components were used. They just want the service to work, to be priced efficiently and for us to take care of all the risks and controls.”

Getting private blockchains like this to work nicely with other major infrastructures is never easy. Citi Token Services is one network; bank consortia, Swift, clearing houses and central banks all run, or are building, others.

“That’s the big ‘I-word’ everyone uses now: interoperability,” says Chatterjee.

He is careful not to let it mean only one thing.

“You need data interoperability, technology and network interoperability, and liquidity interoperability,” he says. “Most of the solutions we’ve seen from fintechs try to solve one of these. But to work truly on a wholesale basis, you need a solution that works across all of them.

“That’s why we’ve created interoperability within Citi’s own systems, between blockchain and non-blockchain.

“The next step is working with partners like Swift, clearing houses and even central banks to make sure interoperability works across the wider wholesale ecosystem.”

The internal step he describes is already in production. In 2025, Citi linked Citi Token Services to its 24/7 USD Clearing service, so tokenised balances in one market can be paid out as conventional US dollar payments around the clock, starting in the UK and US. It is the kind of work Citi keeps in-house: high volume, high client impact and sitting directly on its clearing infrastructure.

None of this moves real volume until a corporate treasurer is prepared to put serious money through a new rail, of course. Chatterjee places blockchain-based money in a line of transitions Citi has taken clients through, including the move from physical to electronic money, and says the test has not changed.

“Trust and reliability are always very important, because with corporate and wholesale clients you’re talking about large sums of money and we act as a fiduciary,” he says. “Cost and efficiency obviously matter, too, but knowing that a bank like us operates in a highly regulated environment, using regulated products, is an element of safety and soundness that clients care a lot about.”

THE KNOWLEDGE GAP

As for the fintechs themselves, Chatterjee credits them with fresh perspectives, an appetite for experimenting with new technology and a habit of sharing the results. Where they fall short is in understanding the businesses they are selling into.

“Wholesale banking and wholesale capital markets are far more complicated under the hood than most people realise,” he says. “So we often see pitches for very simplistic solutions that probably aren’t ready for prime time, which is why we spend a lot of time in our partnership effort getting them ready.”

The good news is that ‘more and more fintechs have people on their management teams with wholesale financial industry experience’. 

“That’s been a big benefit we’ve seen recently,” Chatterjee adds.

Three years out, he expects the arguments the industry is currently having, from traditional versus decentralised finance to which form of digital money wins, to have largely gone away.

“The worlds will merge, as they have across many other ecosystems in the past,” he says. “Clients just care about the benefit; they want the underlying complexity to be invisible.”

If he is correct, clients will stop asking what their money runs on, while BoB continues to help make the right calls in the background.