Demographics, deposits and data: using machine learning to segment UK mortgages

Joe Grimshaw

Who are the UK’s mortgage borrowers, and how do their characteristics differ? Despite extensive literature on mortgage profiles, loan-level segmentation remains limited, existing work relies on aggregates or predefined categories. I address this gap by applying unsupervised machine learning to 20 years of data, allowing the model determine segments without prior assumptions. Three clusters emerge: one with low leverage, and two with high leverage but notably different income profiles. Lending composition has shifted gradually. High leverage, high-income borrowers now account for a larger market share, and first-time buyers increasingly fall into more leveraged segments. Machine learning is crucial for financial stability, revealing concentrations of characteristics, and trends, that aggregates and simple splits cannot, offering richer and earlier indications of potential vulnerabilities.

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Credit constraints and housing market access

Belinda Tracey and Neeltje van Horen

The Help-to-Buy (HTB) programme introduced in 2013 reopened the 95% loan to value (LTV) segment of the UK mortgage market, thereby reducing the minimum deposit requirement for many first-time buyers (FTBs) from 10% to 5% (Chart 1). That policy change offers a useful natural experiment to study how deposit constraints shape access to homeownership. We previously demonstrated that this easing of deposit constraints generated a clear increase in local spending. In a recent paper, we show that lowering this constraint increases FTB home purchases, particularly among households without access to external financial support for their deposit.

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A public-private partnership: central banks as a funding backstop

Matthieu Chavaz, David Elliott and Win Monroe

Large-scale provision of long-term funding to banks has become a central bank tool to support credit supply during downturns. However, scholars have worried that allowing banks to rely on public funding could create moral hazard and crowd out private funding. In a recent paper, we address these concerns by showing that central bank and private funding can be complements rather than substitutes. The mere availability of central bank funding improves private wholesale funding conditions, thus supporting lending without central bank funding being used. This ‘equilibrium’ effect makes central bank funding more powerful than previously thought. Finally, the fact that central bank funding comes with strings attached can help to explain why it is an imperfect substitute for private funding.

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More mortgage lending might push home ownership further out of reach

Jamie Waddell and Danny Walker

Would expanding mortgage supply lead to increased home ownership? Given that 90% of young home owners have a mortgage, it’s tempting to assume the answer is yes. But our analysis suggests that assumption is not necessarily true. We show that increases in mortgage supply have historically had no discernible effect on the home ownership rate and instead tend to push up on house prices, which makes it harder for first-time buyers (FTBs) to afford their first home. They also tend to divert lending towards home-movers and there is some evidence that they increase rents too.

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GIV us some credit: estimating the macroeconomic effects of credit supply shocks

Sam Christie and Aniruddha Rajan

Sudden contractions in credit supply can trigger and amplify recessions – a reality made painfully clear by the 2008 global financial crisis (GFC). However, quantifying these real economic effects is challenging. In this post, we demonstrate a novel way to do so using Granular Instrumental Variables (GIV), focusing on the UK mortgage market. The core idea is that we can exploit the market’s concentration to build up exogenous fluctuations in aggregate credit supply from idiosyncratic lender-specific shocks. Using our GIV, we find evidence that contractionary mortgage supply shocks can have quantitatively significant effects on the macroeconomy, causing persistent decreases in output, consumption, and investment, alongside increases in unemployment.

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30+ year mortgages – are these the new norm? What does this mean for financial stability?

James Waddell and Meghna Shrestha

An increasing number of households in the UK are opting for longer-term mortgages, with the share of borrowers taking out new mortgages with terms 30 years or longer tripling since 2005. But who are these households, why have they done so, and what could this imply for financial stability?

This blog presents some analysis to answer these questions, and focuses on three potential risk channels which could affect financial stability. These can be broadly classified into: (i) lending into old age; (ii) increased leverage; and (iii) higher debt persistence. We judge the risks associated with longer-term mortgages are limited and are mitigated by existing Financial Policy Committee (FPC) and Financial Conduct Authority (FCA) policies, which limit risky lending both at the borrower level and in aggregate.

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Mortgage affordability for borrowers who re-fixed in 2023

Daniel Norris, Elio Cucullo and Vasilis Jacovides

When borrowers enter a fixed-rate mortgage, lenders test whether they could continue to afford their mortgage if interest rates were to increase by the time it comes to re-fix. This ‘stressing’ is designed to create additional resilience for borrowers and the financial system. Over the last two years, mortgage rates have increased by over four percentage points, raising the cost of repayments for those re-fixing. We look at UK mortgage data and compare the stress rates applied at origination to rates available to borrowers when re-fixing. We find that the vast majority of borrowers who came to the end of their fixed terms in 2023 faced new mortgage rates which were lower than those they had been ‘stressed’ at.

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Why lower house prices could lead to higher mortgage rates

Fergus Cumming and Danny Walker

Bank Rate has risen by more than 5 percentage points in the UK over the past couple of years. This has led to much higher mortgage rates for many people. In this post we analyse another potential source of pressure on mortgagors: the potential for falls in house prices to push borrowers into higher – and therefore more expensive – loan to value (LTV) bands. In a scenario where house prices fall by 10% and high LTV spreads rise by 100 basis points, we estimate that an additional 350,000 mortgagors could be pushed above an LTV of 75%, which could increase their annual repayments by an extra £2,000 on average. This could have a material impact on the economy.

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Cost versus availability of loans: which matters more for mortgagors?

Alexandra Varadi

In early 2000s, mortgage debt increased rapidly relative to income. A key driver of this was an expansion in credit supply that made credit cheaper and more widely available. But, it is largely unknown if it is the cost of borrowing or the availability of loans that matters more for mortgagors. I examine this question in a recent paper. I find that increasing loan availability, notably at high loan to value (LTV) or high loan to income (LTI) ratios, increases household borrowing and improves credit access. The cost of borrowing matters too. It is a strong determining factor for mortgagors closer to borrowing limits, and for middle-aged borrowers. And, reducing borrowing costs in tandem with higher loan availability strongly amplifies mortgage borrowing.

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How does house price indexation affect the valuation of equity release mortgages?

Craig Turnbull

Equity Release Mortgages (ERMs) are different from traditional mortgages. Both mortgages provide an upfront cash lump sum. But traditional mortgages are tied to an immediate home purchase that is repaid over a set period, while equity release mortgages are tied to a share of a future home sale. In this blog post, I examine some of the challenges with valuing equity release mortgages. Specifically, I focus on the approaches used to estimate the current home value – a key input to the mortgage valuation – which typically involves applying a simple house price index return to the most recent house survey valuation or transaction price. I show this widespread approach may understate equity release mortgage risks and overstate portfolio values.

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