In the aftermath of the Great Financial Crisis, the Federal Reserve, the international regulatory community, and the banking industry took action to radically improve the safety of the banking system: new capital and liquidity rules, new stress testing requirements, a new resolution framework. Together, these have greatly strengthened the safety of the financial system.
Actual common equity capital ratios for large banks have roughly doubled since the crisis (and are at least six times as great as the pre-crisis requirements). But in implementing these safety requirements, we did not pay as close attention to efficiency.