How does the US Stress Capital Buffer (SCB) work and how is it different from the standard capital conservation buffer?

The Stress Capital Buffer (SCB) is a US-specific innovation that personalizes the capital conservation buffer for each large bank based on supervisory stress test results.

How the SCB is Calculated:

The Federal Reserve runs the annual Comprehensive Capital Analysis and Review (CCAR) / Dodd-Frank stress tests. The SCB equals:

SCB = Max decline in CET1 ratio during the severely adverse scenario + Four quarters of planned common dividends

With a floor of 2.5% (matching the standard CCB).

Example — Two hypothetical banks:

Apex Financial Group has riskier portfolios that suffer more in the stress scenario, so it faces a much higher SCB — essentially the market discipline of stress testing translates directly into a capital requirement.

Key implications:

1. Banks with riskier books face higher buffers automatically
2. The SCB creates incentives to de-risk because a lower stress loss means a lower buffer
3. Unlike the fixed 2.5% CCB in standard Basel III, the SCB is dynamic and updated annually
4. Distribution constraints kick in if CET1 falls below (4.5% minimum + SCB)

This topic is frequently tested on FRM Part II in the context of comparing US implementation versus the Basel Committee's standard framework.

Dive deeper into stress testing frameworks in our FRM Part II course on AcadiFi.