When Challengers Become Incumbents: The New Pressures Facing Neobanks

There’s a version of the challenger bank story that goes: a scrappy fintech disrupts a bloated incumbent, wins on UX, grows exponentially, and traditional banks scramble to catch up. That version was largely true between 2015 and 2021. It’s a less accurate description of 2026.

Monzo, Revolut, and Starling are no longer underdogs. They are, by most measures, established financial institutions, with millions of customers, full banking licences, regulatory scrutiny, and in some cases infrastructure complexity that is starting to look familiar to the institutions they once positioned themselves against.

That shift matters for two audiences: traditional banks and insurers wondering what ‘catching up’ actually means now, and the neobanks themselves, who face a strategic inflexion point their founding narratives didn’t fully account for.

The Problems Scale Creates

Growth solves many problems and creates others. For challenger banks, reaching tens of millions of customers has introduced pressures that were invisible at 100,000 users.

Regulatory burden is the most immediate. Monzo has faced scrutiny from the FCA over financial crime controls. Revolut spent years pursuing a UK banking licence, a process that exposed the gap between operating as an e-money institution and meeting full banking standards. Starling, more deliberately regulated from the outset, navigated this more cleanly, but has not been immune to compliance costs as it scales.

Customer service is another. The ‘everything in-app’ model works elegantly when your customer base is digitally fluent, early adopters. It becomes more complicated when you’re serving 9 million people across a far broader demographic. Monzo has had to build out human support capacity in ways that were never part of the original model.

And then there’s the infrastructure question. Systems built for speed of iteration at low scale don’t always survive the journey to large scale without significant rework. Some technical debt challenges were avoided by not inheriting legacy systems; they’re now beginning to accumulate as the company grows.

Revolut’s Complexity Problem

Revolut is the most interesting case study in what happens when a challenger bank’s ambitions outrun its operational maturity. The product range is extraordinary, including banking, crypto, stock trading, insurance, travel, and business accounts, but the breadth has also created complexity that a focused neobank wouldn’t.

The UK banking licence saga illustrated this clearly. Regulators sought assurances on financial crime controls, governance structures, and operational resilience, which a fast-moving fintech culture found difficult to provide quickly. Revolut eventually secured its UK licence in 2024, but the delay was a signal: moving fast and scaling wide creates regulatory surface area that slows you down.

None of this diminishes what Revolut built. Over 50 million customers is a genuine achievement. But the version of Revolut that exists today is a different kind of institution from the one launched in 2015, and it faces different problems.

Starling’s Strategic Pivot

Starling made a notable strategic decision in 2023: it pulled back from European expansion to focus on consolidating its UK position and building out its B2B banking-as-a-service business, Engine. That’s not the behaviour of a hypergrowth disruptor; it’s the behaviour of a maturing institution making considered capital-allocation decisions.

The engine is genuinely interesting as a business model. It sells Starling’s core banking technology to other banks, effectively monetising the infrastructure it built for itself. But it also represents a shift away from the consumer-challenger narrative toward something more like enterprise software.

That’s not a criticism; it may be exactly the right strategic move. But it’s worth noting that Starling’s growth story and its current strategy are not the same.

What This Means for Traditional Banks

The standard narrative in financial services over the past decade has been: challengers are coming, you need to catch up. That narrative led to significant digital transformation spending with mixed results, because ‘catch up’ was never a sufficiently specific goal.

The more useful framing now is: what specific advantages do challengers still have, and which of those are genuinely replicable?

The UX principles, real-time transparency, frictionless self-service, personalisation, and platform thinking, remain valid and underimplemented at most traditional institutions. Those are worth pursuing with urgency. We covered what that looks like in practice in our piece on

We covered what that looks like in practice in What Challenger Banks Taught Finance About Mobile — And What’s Next.

But the gap is narrowing in ways that change the calculation. Challengers dealing with their own regulatory burden, customer service complexity, and infrastructure rework are less able to out-iterate incumbents than they were five years ago. The window for traditional institutions to close the experience gap, without having to match the structural advantages challengers no longer fully have, is real.

What This Means for Neobanks

The strategic question facing Monzo, Revolut, Starling and others is whether their cultures and operating models can adapt to the demands of institutional scale without losing what made them good products in the first place.

That’s not a trivial transition. The things that make a fast-moving fintech work, flat structures, high autonomy, rapid iteration, and tolerance for rough edges, are genuinely in tension with the things a regulated institution at scale requires. Managing that tension is the defining challenge for this sector over the next decade.

Some will manage it well. Others will find that becoming an incumbent is harder than disrupting one.

The Takeaway

The challenger bank era produced real innovations in financial app design and customer experience that remain underimplemented across most of the industry. Those lessons are still worth learning.

But the ‘challengers vs incumbents’ framing has outlived its usefulness. The more interesting questions are about which firms, traditional or neobank, are building products that genuinely serve customers, can survive regulatory scrutiny at scale, and are making sustainable strategic choices about where to focus.

Those questions don’t have a built-in winner.

The firms that navigate this transition best won’t be the ones who spent the most on transformation; they’ll be the ones who asked the right questions first. If you’re working through where to focus your digital investment in financial services, Sonin’s Discovery Workshops are designed to help you do exactly that. We’ll help you identify the highest-value problems worth solving before you commit to building anything.