This post by Marc Rubinstein offers a short but detailed summary of what has been going on, why and what it means for markets. Read the whole post but one of the key issues for me is increased procyclicality…
The drawback of a heavily collateralized market, though, is its tendency to inject procyclicality into the system. Periods of market turbulence can drive sharply higher collateral requirements, which can prompt more turbulence if that leads to forced selling – such as we saw in the UK last week.
Marc Rubinstein, “Net Interest” Blog – 8 October 2022
This post sets out a case for a bank choosing to incorporate a discretionary Cyclical Buffer (CyB) into its Internal Capital Adequacy Assessment Process (ICAAP). The size of the buffer is a risk appetite choice each individual bank must make. The example I have used to illustrate the idea is calibrated to absorb the expected impact of an economic downturn that is severe but not necessarily a financial crisis style event. My objective is to illustrate the ways in which incorporating a Cyclical Buffer in the target capital structure offers:
an intuitive connection between a bank’s aggregate risk appetite and its target capital structure;
a means of more clearly defining the point where losses transition from expected to unexpected; and
a mechanism that reduces both the pro cyclicality of a risk sensitive capital regime and the tendency for the transition to unexpected losses to trigger a loss of confidence in the bank.
The value of improved clarity, coherence and consistency in the risk appetite settings is I think reasonably self evident. The need for greater clarity in the distinction between expected and unexpected loss perhaps less so. The value of this Cyclical Buffer proposal ultimately depends on its capacity to enhance the resilience of the capital adequacy regime in the face of economic downturns without compromising its risk sensitivity.
There are no absolutes when we deal with what happens under stress but I believe a Cyclical Buffer such as is outlined in this post also has the potential to help mitigate the risk of loss of confidence in the bank when losses are no longer part of what stakeholders expect but have moved into the domain of uncertainty. I am not suggesting that this would solve the problem of financial crisis. I am suggesting that it is a relatively simple enhancement to a bank’s ICAAP that has the potential to make banks more resilient (and transparent) with no obvious downsides.
In Capital 101, we learn that capital is meant to cover “unexpected loss” and that there is a neat division between expected and unexpected loss. The extract below from an early BCBS publication sets out the standard explanation …
Expected and unexpected credit loss
The BCBS publication from which this image is sourced explained that
“While it is never possible to know in advance the losses a bank will suffer in a particular year, a bank can forecast the average level of credit losses it can reasonably expect to experience. These losses are referred to as Expected Losses (EL) ….”
One of the functions of bank capital is to provide a buffer to protect a bank’s debt holders against peak losses that exceed expected levels… Losses above expected levels are usually referred to as Unexpected Losses (UL) – institutions know they will occur now and then, but they cannot know in advance their timing or severity….”
“An Explanatory Note on the Basel II IRB Risk Weight Functions” BCBS July 2005
There was a time when the Internal Ratings Based approach, combining some elegant theory and relatively simple math, seemed to have all the answers
A simple intuitive division between expected and unexpected loss
Allowing expected loss to be quantified and directly covered by risk margins in pricing while the required return on unexpected loss could be assigned to the cost of equity
A precise relationship between expected and unexpected loss, defined by the statistical parameters of the assumed loss distribution
The capacity to “control” the risk of unexpected loss by applying seemingly unquestionably strong confidence levels (i.e. typically 1:1000 years plus) to the measurement of target capital requirements
It even seemed to offer a means of neatly calibrating the capital requirement to the probability of default of your target debt rating (e.g. a AA senior debt rating with a 5bp probability of default = a 99.95% confidence level; QED)
If only it was that simple … but expected loss is still a good place to start
The problem (from a capital adequacy perspective) with both IFRS9 and REL is that the “expected” value still depends on the state of the credit cycle at the time we are taking its measure. REL incorporates a Downturn measure of Loss Given Default (DLGD) but the other inputs (Probability of Default and Exposure at Default) are average values taken across a cycle, not the values we expect to experience at the peak of the cycle downturn.
We typically don’t know exactly when the credit cycle will turn down, or by how much and how long, but we can reasonably expect that it will turn down at some time in the future. Notwithstanding the “Great Moderation” thesis that gained currency prior to the GFC, the long run of history suggests that it is dangerous to bet against the probability of a severe downturn occurring once every 15 to 25 years. Incorporating a measure into the Internal Capital Adequacy Process (ICAAP) that captures this aspect of expected loss provides a useful reference point and a potential trigger for reviewing why the capital decline has exceeded expectations.
One of the problems with advanced model based approaches like IRB is that banks experience large value losses much more frequently than the models suggest they should. As a consequence, the seemingly high margins of safety implied by 1:1000 year plus confidence levels in the modelling do not appear to live up to their promise.
A better way of dealing with uncertainty
One of the core principles underpinning this proposal is that the boundary between risk (which can be measured with reasonable accuracy) and uncertainty (which can not be measured with any degree of precision) probably lies around the 1:25 year confidence level (what we usually label a “severe recession). I recognise that reasonable people might adopt a more conservative stance arguing that the zone of validity of credit risk models caps out at 1:15 or 1:20 confidence levels but I am reasonably confident that 1:25 defines the upper boundary of where credit risk models tend to find their limits. Each bank can makes its own call on this aspect of risk calibration.
Inside this zone of validity, credit risk models coupled with stress testing and sensitivity analysis can be applied to generate a reasonably useful estimate of expected losses and capital impacts. There is of course no guarantee that the impacts will not exceed the estimate, that is why we have capital. The estimate does however define the rough limits of what we can claim to “know” about our risk profile.
The “expected versus unexpected” distinction is all a bit abstract – why does it matter?
Downturn loss is part of the risk reward equation of banking and manageable, especially if the cost of expected downturn losses has already been built into credit risk spreads. Managing the risk is easier however if a bank’s risk appetite statement has a clear sense of:
exactly what kind of expected downturn loss is consistent with the specific types of credit risk exposure the risk appetite otherwise allows (i.e. not just the current exposure but also any higher level of exposure that is consistent with credit risk appetite) and
the impact this would be expected to have on capital adequacy.
This type of analysis is done under the general heading of stress testing for both credit risk and capital adequacy but I have not often seen evidence that banks are translating the analysis and insight into a specific buffer assigned the task of absorbing expected downturn losses and the associated negative impact on capital adequacy. The Cyclical Buffer I have outlined in this post offers a means of more closely integrating the credit risk management framework and the Internal Capital Adequacy Assessment Process (ICAAP).
What gets you into trouble …
“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so”
Commonly, possibly mistakenly, attributed to Mark Twain
This saying captures an important truth about the financial system. Some degree of volatility is part and parcel of the system but one of the key ingredients in a financial crisis or panic is when participants in the system are suddenly forced to change their view of what is safe and what is not.
This is one of the reasons why I believe that a more transparent framework for tracking the transition from expected to truly unexpected outcomes can add to the resilience of the financial system. Capital declines that have been pre-positioned in the eyes of key stakeholders as part and parcel of the bank risk reward equation are less likely to be a cause for concern or trigger for panic.
The equity and debt markets will still revise their valuations in response but the debt markets will have less reason to question the fundamental soundness of the bank if the capital decline lies within the pre-positioned operating parameters defined by the target cyclical buffer. This will be especially so to the extent that the Capital Conservation Buffer provides substantial layers of additional buffer to absorb the uncertainty and buy time to respond to it.
Calibrating the size of the Cyclical Buffer
Incorporating a Cyclical Buffer does not necessarily mean that a bank needs to hold more capital. It is likely to be sufficient to simply partition a set amount of capital that bank management believes will absorb the expected impact of a cyclical downturn. The remaining buffer capital over minimum requirements exists to absorb the uncertainty and ensure that confidence sensitive liabilities are well insulated from the impacts of that uncertainty.
But first we have to define what we mean by “THE CYCLE”. This is a term frequently employed in the discussion of bank capital requirements but open to a wide range of interpretation.
A useful start to calibrating the size of this cyclical buffer is to distinguish:
An economic or business cycle; which seems to be associated with moderate severity, short duration downturns occurring once every 7 to 10 years, and
Every bank makes its own decision on risk appetite but, given these two choices, mine would calibrated to, and hence resilient against, the less frequent but more severe and longer duration downturns associated with the financial cycle.
There is of course another layer of severity associated with a financial crisis. This poses an interesting challenge because it begs the question whether a financial crisis is the result of some extreme external shock or due to failures of risk management that allowed an endogenous build up of risk in the banking system. This kind of loss is I believe the domain of the Capital Conservation Buffer (CCB).
There is no question that banks must be resilient in the face of a financial crisis but my view is that this is a not something that should be considered an expected cost of banking.
Incorporating a cyclical buffer into the capital structure for an Australian D-SIB
Figure 2 below sets out an example of how this might work for an Australian D-SIB that has adopted APRA’s 10.5% CET1 “Unquestionably Strong”: benchmark as the basis of its target capital structure. These banks have a substantial layer of CET1 capital that is nominally surplus to the formal prudential requirements but in practice is not if the bank is to be considered “unquestionably strong” as defined by APRA. The capacity to weather a cyclical downturn might be implicit in the “Unquestionably Strong” benchmark but it is not transparent. In particular, it is not obvious how much CET1 can decline under a cyclical downturn while a bank is still deemed to be “Unquestionably Strong”.
The proposed Cyclical Buffer sits on top of the Capital Conservation Buffer and would be calibrated to absorb the increase in losses, and associated drawdowns on capital, expected to be experienced in the event of severe economic downturn. Exactly how severe is to some extent a question of risk appetite, unless of course regulators mandate a capital target that delivers a higher level of soundness than the bank would have chosen of its own volition.
In the example laid out in Figure 2, I have drawn the limit of risk appetite at the threshold of the Capital Conservation Buffer. This would be an 8% CET1 ratio for an Australian D-SIB but there is no fundamental reason for drawing the lone on risk appetite at this threshold. Each bank has the choice of tolerating some level of incursion into the CCB (hence the dotted line extension of risk appetite). What matters is to have a clear line beyond which higher losses and lower capital ratios indicate that something truly unexpected is driving the outcomes being observed.
What about the prudential Counter-Cyclical Capital Buffer?
I have deliberately avoided using the term”counter” cyclical in this proposal to distinguish this bank controlled Cyclical Buffer (CyB) from its prudential counterpart, the “Counter Cyclical Buffer” (CCyB), introduced under Basel III. My proposal is similar in concept to the variations on the CCyB being developed by the Bank of England and the Canadian OFSI. The RBNZ is also considering something similar in its review of “What counts as capital?” where it has proposed that the CCyB should have a positive value (indicatively set at 1.5%) at all times except following a financial crisis (see para 105 -112 of the Review Paper for more detail).
My proposal is also differentiated from its prudential counter part by the way in which the calibration of the size of the bank Cyclical Buffer offers a way for credit risk appetite to be more formally integrated with the Internal Capital Adequacy Process (ICAAP) that sets the overall target capital structure.
Incorporating a Cyclical Buffer into the target capital structure offers a means of more closely integrating the risk exposure and capital adequacy elements of a bank’s risk appetite
A breach of the Cyclical Buffer creates a natural trigger point for reviewing whether the unexpected outcomes was due to an unexpectedly large external shock or was the result of credit exposure being riskier than expected or some combination of the two
The role of the Capital Conservation Buffer in absorbing the uncertainty associated with risk appetite settings is much clearer if management of cyclical expected loss is assigned to the Cyclical Buffer
This post is irredeemably technical so stop here if that is not your interest. If you need to understand some of the mechanics of the formula used to calculate credit risk weighted assets under the advanced Internal Ratings Based (IRB) approach then the BCBS published a paper in 2005 which offers an explanation:
describing the economic foundations
as well as the underlying mathematical model and its input parameters.
While a lot has changed as a result of Basel III, the models underlying the calculation of Internal Rating Based Capital (IRB) requirements are still based on the core principles agreed under Basel II that are explained in this BCBS paper.
The notes in the linked page below mostly summarise the July 2005 paper with some emphasis (bolded text) and comments (in italics) that I have added. The paper is a bit technical but worth reading if you want to understand the original thinking behind the Basel II risk weights for credit risk.
I initially found the paper useful for revisiting the foundation assumptions of the IRB framework as background to considering the regulatory treatment of Expected Loss as banks transition to IFRS9. The background on how the RW was initially intended to cover both Expected and Unexpected Loss, but was revised such that capital was only required to cover Unexpected Loss, is especially useful when considering the interaction of loan loss provisioning with capital requirements.
Reading the BCBS paper has also been useful for thinking through a range of related issues including:
The rationale for, and impact of, prudential conservatism in setting the risk parameters used in the IRB formula
The cyclicality of a risk sensitive capital requirement (and potential for pro cyclicality) and what might be done to mitigate the risk of pro-cyclical impacts on the economy
I am not a credit risk model expert, so the summary of the paper and my comments must be read with that in mind. I did this to help me think through some of the issues with bank capital adequacy. Hopefully others will find the notes useful. If you see something wrong or something you disagree with then let me know.