The Bank of England is reshaping how it manages the plumbing of the UK financial system. Governor Andrew Bailey has laid out a policy framework focused on continuing to shrink the central bank’s balance sheet through quantitative tightening while transitioning to a system where reserve supply is driven by actual bank demand, not legacy crisis-era holdings.

The numbers behind the wind-down

UK central bank reserves sat at £643.5B as of early 2026, down £63.2B from March 2025. That’s a meaningful decline, but the reserves are still well above what the BoE considers the sweet spot.

That sweet spot has a name: the Preferred Minimum Range of Reserves, or PMRR. The current estimate puts the PMRR at £365B to £515B, recently updated from a previous range of £345B to £490B. The banking system probably needs somewhere between £365B and £515B in reserves to function smoothly, and the BoE is still holding about £130B more than the top end of that range.

Bailey first introduced the PMRR concept in a lecture on May 21, 2024, arguing that banks need higher reserve levels than pre-2008 norms to maintain financial stability. The updated range reflects a more refined understanding of banks’ day-to-day transactional demands.

On the gilt side, the BoE has offloaded over £300B in holdings since 2022. As of December 2025, roughly £553B remained on the balance sheet.

Why the BoE wants out of the gilt business

Central banks bought enormous quantities of government bonds during quantitative easing to push down long-term interest rates and stimulate the economy. The problem is that holding those bonds exposes the central bank to interest rate risk. When rates rise, the value of those bonds falls, and the central bank takes losses. Every pound of loss on the BoE’s balance sheet is ultimately a cost borne by the UK Treasury.

The operational side of this shift involves tweaking the BoE’s lending facilities. The Short-Term Repo and Indexed Long-Term Repo facilities are being adjusted to better match how banks actually want to access liquidity. Rather than flooding the system with reserves and hoping banks figure out what to do with them, the BoE is moving toward a model where banks pull reserves as needed through these facilities.

What this means for markets and investors

For the banking sector, the transition introduces some uncertainty. Banks have grown accustomed to swimming in excess reserves. As that pool shrinks toward the PMRR, banks will need to be more deliberate about their liquidity management. The adjusted repo facilities are designed to cushion this transition.

The key number to monitor going forward is how quickly reserves approach the upper bound of the PMRR at £515B. At the current pace of roughly £63B per year in reserve reduction, the BoE could reach that threshold within about two years. What happens as reserves enter the PMRR range will be the real test of whether the demand-driven model works as advertised, or whether the transition triggers the kind of money market stress that forced the Fed to abruptly end its last QT cycle in 2019.