The Common Equity Tier 1 (CET1) ratio compares a bank's highest-quality regulatory capital with its risk-weighted assets.
CET1 ratio = CET1 capital ÷ risk-weighted assets
CET1 capital consists primarily of common stock and retained earnings, after required regulatory adjustments and deductions.
Why risk-weighted assets matter
The denominator is not total accounting assets. Regulatory rules assign different risk weights to assets and exposures, so two banks with the same total assets can have very different risk-weighted assets and CET1 ratios.
That means changes in the ratio can come from:
- retained earnings or losses;
- dividends and share repurchases;
- acquisitions;
- changes in loan and securities mix;
- credit deterioration;
- regulatory deductions; or
- changes in risk-weighted assets.
CET1 ratio versus book equity
The CET1 ratio is not the same as common equity ÷ total assets and is not the same as Return on Equity.
Accounting equity and regulatory capital overlap, but regulatory capital applies specific eligibility rules, adjustments, deductions, and risk weighting.
Minimum requirements are not the whole story
Federal Reserve rules specify minimum capital ratios, but a large bank's effective CET1 requirement can also include a stress capital buffer and, where applicable, additional surcharges.
Community banks using the Community Bank Leverage Ratio framework may not be required to report a CET1 ratio at all.
Investor interpretation
A higher CET1 ratio generally means a larger regulatory capital cushion relative to risk-weighted assets, but more capital is not automatically better for shareholder returns. Investors should evaluate capital together with credit risk, growth, payout policy, stress-test requirements, and return on equity.
Sources
- Federal Reserve, Data Sources and Terms, June 2026
- Federal Reserve Regulation Q, Minimum Capital Requirements
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