Wednesday, January 1, 2014
A discussion on a blog with someone who insisted that it is ok for the current capital requirements for banks to be higher for those perceived as risky that for those perceived as absolutely safe “because of the volatility”; and called me stupid because I “appear not to understand the whole concept of expected and unexpected losses” made me realize that I had to clarify again The Basel Mistake… namely that Basel II (and III) base the capital requirements for banks which are to cover for the “unexpected losses” on the same perceptions that guides the “expected losses”.
“The model [is] portfolio invariant and so the capital required for any given loan does only depend on the risk of that loan and must not depend on the portfolio it is added to.”
And the explicit reason for that mindboggling simplification was because it was:
“This characteristic has been deemed vital in order to make the new IRB framework applicable to a wider range of countries and institutions. Taking into account the actual portfolio composition when determining capital for each loan - as is done in more advanced credit portfolio models - would have been a too complex task for most banks and supervisors alike.”
And which then leads to:
“In the context of regulatory capital allocation, portfolio invariant allocation schemes are also called ratings-based. This notion stems from the fact that, by portfolio invariance, obligor specific attributes like probability of default, loss given default and exposure at default suffice to determine the capital charges of credit instruments. If banks apply such a model type, they use exactly the same risk parameters for expected losses (EL) and unexpected losses (UL), namely probability of default (PD), loss given default (LGD) and exposure at default (EAD).”
And to justify their approach they write:
In the specification process of the Basel II model, it turned out that portfolio invariance of the capital requirements is a property with a strong influence on the structure of the portfolio model. It can be shown that essentially only so-called Asymptotic Single Risk Factor (ASRF) models are portfolio invariant (Gordy, 2003). ASRF models are derived from “ordinary” credit portfolio models by the law of large numbers. When a portfolio consists of a large number of relatively small exposures, idiosyncratic risks associated with individual exposures tend to cancel out one-another and only systematic risks that affect many exposures have a material effect on portfolio losses. In the ASRF model, all systematic (or system-wide) risks, that affect all borrowers to a certain degree, like industry or regional risks, are modeled with only one (the “single”) systematic risk factor
But suspecting they might be simplifying beyond reason, just in case, the Basel Committee added:
“It should be noted that the choice of the ASRF for use in the Basel risk weight functions does by no means express any preference of the Basel Committee towards one model over others. Rather, the choice was entirely driven by above considerations. Banks are encouraged to use whatever credit risk models fit best for their internal risk measurement and risk management needs.”
And this very flimsy approach, which ignores any correlation between unexpected losses, and shows very little concern with the problems of rapidly changing volatility, caused the Basel Mistake of setting the capital requirements based on exactly the same perceived risks already cleared for.
In essence the regulators determined that a “risky” creditor, by the single fact of presenting more “expected losses”, also had to provide for more capital to cover for more “unexpected losses”
And this the regulator did without absolutely any concern for how that could affect the efficiency of bank credit allocation in the real economy… something that can also be derived from the tragic fact that nowhere in the Basel Committee literature is there a word about the purpose of our banks.
And so they introduced an odious regulatory discrimination against those perceived as “risky”, something which introduces a dangerous risk-aversion, and, consequentially, introduces a favoring of what is perceived as “absolutely safe” that can only guarantee the dangerous overcrowding of safe-havens.
In essence bank regulators have converted themselves into the greatest systemic risk producers to the banking system.
In short we do not need bank regulators, what we need are regulators who understand the banking system.
In short we need regulators who understand that more important than looking at the portfolio of individual banks, is to look at the portfolio of banks in the whole banking system... and how it relates to the real economy.
Perhaps our bank regulators do not understand the concept of "regression to the mean"