At present, the definition of capital, the deductions from it, the definitions of riskweighted assets, and the calibration of both the minimum requirement and the buffer all  4  http://www.bis.org/press/p091217.htm. 5  Banks should carry enough capital to absorb credit losses and declines in trading book asset values associated with changes in economic fundamentals.
On the other hand, it is a waste of society’s resources to expect them to also carry capital to cover unrealized losses that arise simply because market prices have become unhinged from economic fundamentals due to transitory factors, such as a breakdown in market liquidity. BIS Review 81/2010  3  remain to be finalised.