Risk aggregation has been a challenge to risk practitioners for a long time. This was largely
due to the variety of risk measures applied to the different risk silos, and the correlations that
exist between risks. The recent development of a common denominator measure for market,
credit and operational risks enables firms to aggregate their quantifiable risks into a total risk
estimate. The emerging common denominator of quantifiable risks is called Economic (Risk)
Capital.
Economic Capital is the amount of capital that could be used to cover all liabilities in a worst
case scenario – unexpected market, credit, operational and/or insurance loss.7
The conceptual
appeal of Economic Capital methods, as recognised recently by the regulator, is that ‘they can
provide a single metric along which all types of risks can be measured’ (BIS 2003: 6). Even
though there are a number of ways for the calculation of Economic Capital as assumptions
and data used to feed the models may vary from bank to bank all Economic Capital
frameworks are conceptually identical.
The Basel Committee has also legitimised the Economic Capital methodology that in the last
decade has emerged as best practice among practitioners (see for example Marrison 2002).
But the real institutional force behind the spreading of Economic Capital in the industry is the
rating agency community. Banks tailor Economic Capital not to a regulatory standard, but to
the capital adequacy expectations coming from rating agencies. Economic Capital is the
measure of the maximum probable loss that the bank must appear to be able to withstand in
order to justify its target credit rating.
Given that rating agency opinions concern different banks to different extent, Economic
Capital (or its promise) appeals primarily to banks that wish to maintain a high credit rating.
For example, firms rated AA by Standard & Poor’s (S&P) have historically defaulted with a
0.03 per cent probability over a one-year horizon. If a bank aims for an AA credit rating, then
the corresponding capital level (Economic Capital) is the amount required to keep the firm
solvent over a one-year period with 99.97 per cent confidence (Garside & Nakada 1999).
Given the higher confidence level applied, the ‘economic’ capital amount is to be higher than
the regulatory minimum.
Economic Capital, as a measurement tool is, in effect, a restatement of value-at-risk amounts
using a set of parameters that corresponds to a solvency standard (rather than to the regulatory
rules). It can be calculated on market, credit and (measurable) operational risks, with the help
of judgment where data is not sufficient or cannot be simulated (especially in case of
operational risk).
Furthermore, Economic Capital is recognised by the new Basel II framework as a promising
tool for financial institutions to allocate capital internally across the business units. This is
because of the ability of the Economic Capital technique to aggregate risk (measured in risk
silos) in a given subsidiary. While internal capital allocation is a regulatory requirement,