The cost of excess liquidity: why banks need to rebalance now

Since the global financial crisis, banks have been holding onto large cash reserves, treating size as a proxy for security. But as higher interest rates have reshaped the economic environment, what if, rather than strengthening resilience, those buffers are now suppressing returns? We examine the true cost of excess liquidity and how banks could benefit from a more dynamic approach that balances risk with growth.  

Many banks today hold liquidity buffers well above what regulation requires. Although the Liquidity Coverage Ratio (LCR) sets a regulatory floor of 100%, most large institutions run at 130–150%, and some even higher.

On paper, holding onto large reserves seems sound. Higher buffers can provide a sense of safety and they are easy to defend internally. But, past a certain threshold, large buffers quickly become a structural constraint, tying up balance-sheet capacity and limiting how it can be used. In an environment of tighter funding and higher interest rates, excess liquidity erodes earning power and ties up capacity that could otherwise support growth.

This doesn’t mean that buffers don’t matter, just that stability can’t be achieved through buffer size alone. What really matters is how well an organisation understands liquidity and manages it across the balance sheet. In this series of five articles, we explore how banks can rebalance risk and growth, evolving from static buffers to dynamic and integrated liquidity management.

We open by looking at why holding buffers above the regulatory minimum has become more commonplace, why this strategy could be costing banks more than they think, and how rebalancing can free up valuable capacity to improve returns and strengthen resilience.

How excess liquidity became the default

The roots of the pattern go back to the global financial crisis. In its aftermath, regulators introduced tougher liquidity requirements, and many banks responded by building up cash reserves well beyond what those new rules demanded.

The trouble is that once liquidity has accumulated, it can be very hard to unwind. This is due to several structural factors:

• Operational reality: redeploying liquidity at scale is rarely frictionless, particularly where systems or execution capacity lag
• Structural traps: borders between jurisdictions and legal entities can prevent efficient redeployment of liquidity across the group
• Behavioural conservatism: risk appetite resets slowly after a crisis, particularly at board level
• Model-driven caution: stress-testing and liquidity frameworks embed conservative assumptions, particularly where behavioural insight or data granularity is limited
• Governance friction: approval processes make it harder to reduce buffers than increase them.

While none of these forces on its own is enough to keep buffers elevated, their combined effect makes rebalancing especially challenging. Once buffers rise, holding onto them becomes the path of least resistance, since bringing them down requires coordinated decisions across risk, treasury, and the business.

Where excess liquidity starts to cost

Holding higher buffers can create significant economic drag. Every additional 10–20% of LCR can represent billions held in lower-yielding assets.

While HQLA provides important operational flexibility and alternative uses of the balance sheet carry additional capital and risk costs, surplus liquidity still has a material opportunity cost. For Tier 1 banks, even a relatively small gap in risk-adjusted returns across substantial balance-sheet volumes can translate into significant foregone income. This puts the focus on buffers held beyond genuine regulatory and operational needs, where there is often scope for selective redeployment.

The regulatory reality, and its limits

The aim of regulations is to ensure compliance, but regulators also know this comes with a trade-off. While higher liquidity ratios reduce systemic risk, they also weigh on credit growth and capital efficiency.

In practice, the system tends to favour conservatism. Supervisors are quick to flag a shortfall, but rarely challenge a buffer that’s very large. Internal governance mirrors this dynamic, leaving little upside for optimisation and clear downside for getting it wrong. As a result, liquidity decisions often get treated as a risk problem rather than a return one, and challenging that framing isn’t easy.

Rebalancing is more than a firm-level choice

If buffers were reduced across multiple institutions at the same time, the effects would be felt beyond individual balance sheets in:

• Credit expansion: increased lending capacity as constraints ease
• Market repricing: tighter spreads across corporate credit and other risk assets as liquidity seeks yield
• Supervisory response: heightened scrutiny, and potentially regulatory recalibration, if systemic risk rises.

The reality is that decisions made by individual institutions can have market-wide effects, which is why liquidity strategy cannot be reduced to a treasury decision alone.

Why rebalance now?

For years, the cost of excess liquidity was seen as the price of resilience. This view is harder to justify today because the economics have shifted. Funding has gotten more expensive, capital efficiency is under pressure, and liquidity risks are showing up faster and less predictably than legacy frameworks were built to handle.

In many institutions, large buffers have also become a substitute for confidence in underlying models. Liquidity and interest rate risk frameworks were built for a more stable environment, and as those assumptions have aged, buffers have expanded to compensate. Holding more liquidity often feels like the safer option, and it’s definitely easier than recalibrating models, but it just moves uncertainty onto the balance sheet, where it costs more to carry.

Of course, banks still need to hold liquidity, but the more interesting questions are how much they retain and how deliberately they manage it. Static buffers made sense when uncertainty was cheaper to absorb. Today, resilience depends more on understanding how liquidity risk actually plays out, and on managing it actively rather than simply holding more of it.

Closing thought

Making the shift from holding buffers to actively managing resilience is where the opportunity now lies. To redeploy capacity, banks must be able to:

• Trust the models behind it
• Understand the behavioural insights driving liquidity
• Shape the architecture that allows them to act on these insights effectively
• Navigate digital assets, which transform how quickly liquidity can move.

We explore each of these topics in more detail throughout the rest of this series.