Risk-weighted capital - Whose model is it anyway?

A simple way to judge the solidity of a bank is to compare the amount of money it can afford to lose without keeling over to the size and riskiness of its business. After the financial crisis, regulators sensibly worked to boost the first figure: banks now fund their lending less with money they borrow themselves, often from depositors, and more with capital belonging to their shareholders. That was the easy bit. Trying to get to the bottom of how risky banks are, and so how much capital each requires, is now top of regulators’ minds. Beyond further denting the sector’s profits, the outcome of their review threatens to introduce risks of its own.

The Economist