Measuring capital at risk in the UK banking sector – Bank Underground

Giovanni Covi, James Brookes and Charumathi Raja

How banks are uncovered to the monetary system and real-economy determines focus threat and interconnectedness within the banking sector, and in flip, the severity of tail-events. We assemble the Global Network data set, a complete exposure-based information set of the UK banking sector, up to date quarterly, overlaying roughly 90% of complete belongings. We use it to review the UK banking system’s microstructure and estimate the probability and severity of tail-events. We discover that throughout the Covid-19 (Covid) pandemic, the probability and severity of tail-events within the UK banking sector elevated. The chance of an excessive stress occasion with losses above £91 billion (roughly 19% of CET1 capital) elevated from 1% earlier than the pandemic to 4.1% in 2020 Q2, subsequently falling to 1.7% in 2021 This autumn.

The position of focus threat and interconnectedness within the financial and monetary system

Concentration risk within the financial system, resembling vulnerability to shocks to giant non-financial firms, might result in exceptional fluctuations in financial exercise (Gabaix (2011)). The extent of interconnectedness in financial exercise, resembling a excessive stage of interdependency within the intersectoral input-output linkages of corporations, that’s, how a agency’s output is used within the manufacturing perform of one other agency as enter, might clarify mixture fluctuations in output (Acemoglu et al (2012)). These community options – focus threat and interconnectedness – additionally play an essential position throughout the monetary system in figuring out fluctuations within the stage of systemic threat. Stress-testing fashions geared toward capturing tail-risk interdependence and the extent of systemic threat want due to this fact to take these community options under consideration, in order to mannequin the monetary system’s stability by the lens of its market microstructure.

Stochastic microstructural stress-testing fashions

Creating insurance policies that cut back the build-up of systemic threat and protect the steadiness of the monetary system is an more and more related job for regulators worldwide. The chance surroundings is constantly evolving, and dangers might come up from throughout the system relying on how banks’ exposures are distributed throughout asset courses, corporations, sectors and international locations. This requires creating sound analytical instruments to interpret and forecast dangers. There are totally different methodologies aiming at assessing the propagation of dangers from the true financial system to the banking sector’s stability sheet. On this submit, we use a microstructural stress-testing methodology to evaluate solvency threat. This system may be very useful as a result of it permits regulators to decompose the sources of threat based on every particular person part of the community, and carry out ad-hoc counterfactual coverage workout routines.

Our modelling method measures solvency threat of the UK banking sector as a perform of:

1. The community construction of UK banks’ exposures, thereby capturing the position performed by interconnectedness and focus threat.
2. Counterparty threat resembling counterparties’ chance of default (PD) and loss given default (LGD) parameters, capturing the severity of potential shocks (one yr forward) to the true financial system. This set of parameters is estimated by UK banks based on the sector and nation of the counterparty utilizing obligor stage information and they’re supplied as supervisory information COREP template C.09.02.
3. A correlation matrix of counterparties’ default chances, which goals to approximate the inter-sectoral input-output linkages of corporations and so fashions tail-risk interdependence.

Lastly, we carry out this system for 20,000 simulations with a purpose to derive a full distribution of banks’ losses and so mannequin situation uncertainty over time. This stochastic method to situation design permits us to seize your complete spectrum of the severity of potential stress occasions and assess their consequence in probabilistic phrases. Additional particulars concerning the methodology and outcomes are supplied in this working paper. 

Measuring capital in danger

We derive two forward-looking measures of solvency threat (one yr forward) – a capital in danger measure (CAR) and a conditional capital in danger measure (CCAR). The previous goals to trace the build-up of anticipated losses or common threat within the UK banking sector, whereas the latter is calibrated to the 99th percentile of the loss distribution to seize excessive stress occasions or to the 97.fifth percentile, to seize extreme stress occasions. We due to this fact monitor the build-up of the typical and tail dangers within the UK banking sector and examine their probability over time, specializing in sizing the build-up of tail-risk throughout the Covid pandemic.

Massive granular information units

We assemble the International Community information set, which includes of mortgage, safety and spinoff exposures from quite a lot of totally different information units collected for supervisory functions – Desk A. This covers roughly £9.4 trillion or 90% of the UK banking system’s belongings. The information set persistently maps UK banks’ exposures to counterparties throughout numerous sectors of the financial system and international locations. The information set is split into two major classes of exposures. Granular exposures discuss with exposures mapped at an entity-to-entity stage which account for 43% of complete publicity quantities (£4.1 trillion). The remaining mixture exposures at mapped at a sector-country stage.

Desk A: The worldwide community information set (£ billion)

Notice: GG refers to common authorities, FC to non-bank monetary firms, CI to credit score establishments, HH to the family sector, NFC to non-financial firms and CB to central banks.

Outcomes

We discover that the chance of experiencing an excessive stress occasion above £91 billion losses which is the same as 19% of UK banking system’s CET1 capital (3.4 instances the typical loss) reached its peak of 4.1% in 2020 Q2, from 1% throughout the pre-pandemic interval (left-hand panel, Chart 1). Furthermore, the severity of maximum stress occasions has additionally elevated, with CCaR estimates amounting to £147 billion, nearly 62% increased in comparison with the pre-pandemic interval. Equally, the probability and severity of extreme (97.fifth percentile) stress occasions has elevated too. Most of this enhance is because of increased counterparty threat within the company sector (increased PDs) and as a result of build-up of threat outdoors the UK. Final, we estimated anticipated losses (CaR) – the imply of the loss distribution – which averaged at £27 billion pre-pandemic and £37 billion on the peak of the disaster, representing a rise of 36%. In 2021 This autumn, the CaR estimate was nonetheless above the pre-pandemic stage and near £31 billion.

Chart 1: Chance and severity of tail occasions within the UK banking sector

Conclusions and coverage implications

The chance and severity of maximum stress occasions within the banking sector relies upon, to start with, on the extent of fragility in the true financial system, that’s, on present financial and monetary situations that are captured by the set of threat elements – PD and LGD parameters. Nonetheless, banks’ publicity to the true financial system and the monetary system additional exacerbate the severity of uncommon tail occasions in addition to enhance their chance. Because of stochastic microstructural stress-testing methodologies, we’re capable of assess how the microstructure of the banking system and its defining options – focus threat and interconnectedness – collectively with the construction of the true financial community play a key position within the realisation of such uncommon excessive stress occasions just like the 2008 Nice Monetary Disaster. The exact same probabilistic situation might lead to a really totally different consequence relying on how monetary and actual financial relationships are distributed, and on the set of corporations which are negatively affected by the deterioration in financial and monetary situations, that’s, the distribution of shocks. Total, the next stage of counterparty threat in the true financial system, or the next stage of input-output integration amongst corporations in the true financial system, and a extra interconnected and concentrated banking system’s community of exposures enhance the severity and chance of uncommon tail occasions affecting the banking sector. This microstructural method has been utilized to measure the impression of the Covid pandemic on the UK banking sector’s chance of experiencing such excessive stress occasions. We discovered that this chance has elevated by 310% at its peak in 2020 Q2 and nonetheless in 2021 This autumn stays increased in comparison with pre-pandemic ranges resulting from increased counterparty threat.

Giovanni Covi works within the Financial institution’s Stress Check Technique Division, James Brookes works within the Financial institution’s Superior Analytics Division and Charumathi Raja works within the Financial institution’s Banking Capital Coverage Division.

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