Static capital buffer outperforms complex dynamic rules
A Federal Reserve working paper argues that simple static capital buffers are more effective than complex dynamic rules in preventing excessive bank risk-taking. The study finds that implementable dynamic rules, including Basel III guidance, perform poorly compared to a small, static buffer.
The 'no-failure' ideal vs. reality
The paper develops a dynamic macroeconomic model where deposit insurance and limited liability incentivize banks to engage in socially inefficient risk-taking.
While high capital requirements can curb this, they also reduce liquidity from bank deposits.
The authors devise an optimal 'no-failure' rule that sets capital requirements just high enough to prevent excessive risk-taking and bank failures.
However, this rule is not implementable as it requires full knowledge of all economic shocks.
In contrast, simpler rules that respond to cyclical conditions, such as those aligned with Basel III guidance, are shown to perform poorly.
The study concludes that a small static capital buffer can achieve significantly better outcomes than these complex, yet implementable, dynamic approaches.
Basel III guidance falls short
The paper critically evaluates simple implementable rules for capital requirements, including Basel III guidance for the countercyclical capital buffer (CCyB).
This guidance suggests adjusting capital based on cyclical conditions like credit expansion.
While empirical evidence supports the credit-to-GDP ratio as a predictor, the study's theoretical model shows that optimizing such a rule results in a vanishingly small coefficient.
Consequently, simple dynamic rules do not meaningfully improve upon a static buffer.
The authors find that a slightly elevated static capital requirement largely avoids 'Wile E. Coyote moments'—sudden, unexpected crises—and performs nearly as well as the optimal linear rule in welfare terms.
Simplicity trumps complexity
This paper delivers a potent challenge to the prevailing belief in complex, dynamic capital buffers.
It suggests that the pursuit of finely tuned countercyclical adjustments may be a regulatory overreach, prone to miscalibration and unexpected failures.
The findings strongly advocate for a return to simpler, more robust capital frameworks, implying that sometimes, less truly is more in financial regulation.