Caterina Mendicino, Kalin Nikolov, Juan Rubio-Ramirez, Javier Suarez, Dominik Supera, 24 February 2021

Well-capitalised banks make the financial system more resilient to episodes such as the COVID-19 crisis. This column assesses how much capital would be optimal for banks to hold, taking into consideration the risk of banking crises driven by borrower defaults. It finds that capital requirements of around 15% provide the optimal trade-off between lowering the frequency of banking crises caused by borrower defaults and maintaining the availability of credit in normal times. While the exact figure depends on a number of assumptions, it is higher than both the Basel III minimum and the optimum implied by macroeconomic frameworks that underestimate or neglect the impact of borrower default on bank solvency.

Gene Ambrocio, Esa Jokivuolle, 14 May 2018

The Basel III reform raised banks’ capital requirement per risk-weighted assets considerably, while risk weights were largely unchanged. This column uses a simple model to explore whether these risk weights discourage productive business investments. The model shows that when firms face collateral constraints, the optimal risk weights on corporate loans should be ‘flatter’ than they are at present. A quantitative assessment, however, suggests that welfare losses from the current system may not be large.

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