What is the Common Equity Tier 1 (CET1)?

Common Equity Tier 1 (CET1) is a key measure of a bank's financial strength and stability, particularly regarding its ability to absorb losses in times of financial stress. It represents the core capital of a bank, primarily consisting of common shares and retained earnings, which is used to meet regulatory capital requirements. CET1 is one of the most scrutinized metrics by regulators, investors, and analysts to assess the risk profile and health of financial institutions.

Regulatory Background

The concept of CET1 emerged as part of the Basel III framework, a set of international banking regulations developed by the Basel Committee on Banking Supervision. After the 2008 financial crisis, it became clear that many banks were inadequately capitalized to withstand significant losses, contributing to the crisis's severity. As a result, regulatory bodies aimed to increase the quantity and quality of capital that banks hold, leading to the introduction of CET1.

Before Basel III, Tier 1 capital was used as the primary indicator of a bank’s capital strength, but it included instruments like preferred shares and hybrid debt, which were not as effective in absorbing losses. Basel III introduced CET1 to narrow the focus to the highest quality capital, emphasizing that common equity is the most reliable buffer during financial downturns.

Components of CET1

CET1 primarily includes:

1. Common Stock: The most fundamental component of CET1 is the bank’s issued common shares. This refers to the ordinary shares held by shareholders, which represent ownership in the bank.
2. Retained Earnings: Profits that the bank has earned over time but not paid out as dividends are included in CET1. Retained earnings are critical because they provide a cushion against future losses.
3. Accumulated Other Comprehensive Income (AOCI): This includes unrealized gains and losses on assets that are available for sale, such as government securities or foreign currency translations. Though these gains or losses haven't been realized (i.e., the assets haven’t been sold), they still affect the bank’s capital position and are part of CET1.
4. Deductions: Certain items are subtracted from CET1, including:

• Goodwill: An intangible asset that can’t be used to absorb losses.
• Deferred Tax Assets: Future tax benefits that depend on the bank’s future profitability.
• Investments in financial institutions: To avoid double-counting capital, certain investments in other banks or financial institutions must be deducted from CET1.

1. Minority Interests: In some cases, CET1 can include minority interests, which represent the portion of a subsidiary’s common equity not owned by the parent company. However, strict conditions must be met for these to be included in CET1.

Importance of CET1 in Bank Regulation

The primary purpose of CET1 is to ensure that banks have enough high-quality capital to absorb losses without triggering a financial crisis. Regulatory bodies set minimum CET1 ratios to ensure that banks are adequately capitalized. These ratios are expressed as a percentage of a bank’s risk-weighted assets (RWA).

1. Risk-Weighted Assets (RWA): RWAs are a measure of a bank’s exposure to risk. Assets are weighted according to their risk profile. For example, a government bond is typically considered less risky than a corporate loan, so it has a lower risk weight. The riskier the asset, the higher the risk weighting, and the more CET1 capital a bank needs to hold against that asset.
2. Minimum CET1 Requirements: Under Basel III, banks are required to maintain a minimum CET1 ratio of 4.5% of their RWAs. In addition, banks must hold additional capital buffers:

• Capital Conservation Buffer: An additional 2.5% of RWAs that banks must hold to absorb losses during periods of economic stress.
• Countercyclical Buffer: An extra buffer that can be required by national regulators during times of excessive credit growth to prevent financial instability.

Together, these buffers mean that many banks must maintain a CET1 ratio well above the 4.5% minimum to avoid penalties and restrictions, such as limits on dividend payments or share buybacks.

CET1 and Stress Testing

Stress tests are another key tool used by regulators to assess the resilience of banks, and CET1 is central to these tests. A stress test simulates adverse economic conditions (such as a recession or financial market collapse) to determine whether a bank would have enough capital to survive.

In these tests, regulators project losses on loans, securities, and other exposures under different stress scenarios, and they assess how those losses would impact a bank’s CET1 capital. A bank that fails a stress test may be required to raise additional capital, restrict shareholder payouts, or reduce risky assets to strengthen its capital position.

CET1 vs. Other Tiers of Capital

While CET1 is considered the highest quality capital, banks also hold other types of regulatory capital, such as:

1. Additional Tier 1 (AT1) Capital: This consists of instruments like non-cumulative preferred shares and contingent convertible bonds (CoCos). While AT1 capital can absorb losses, it is not as reliable as CET1 because it may only absorb losses under certain conditions, such as when a bank’s CET1 ratio falls below a specific threshold.
2. Tier 2 Capital: This includes subordinated debt and other hybrid instruments that are further down the hierarchy of loss absorption. These instruments are typically not as permanent or reliable as CET1, which is why they are considered lower-quality capital.

Together, CET1, AT1, and Tier 2 capital form the total capital that a bank holds to meet regulatory requirements. However, CET1 is the most critical component, as it represents the most immediate and reliable buffer against losses.

Market Impact and Investor Perspective

Investors closely monitor a bank’s CET1 ratio because it is a key indicator of financial strength and risk. A higher CET1 ratio generally signals that a bank is better capitalized and less likely to face financial distress in adverse conditions.

From an investment perspective, a strong CET1 ratio can support a bank’s ability to pay dividends or repurchase shares. However, if a bank’s CET1 ratio falls too low, it may be restricted from making these distributions, which can negatively affect shareholder returns.

Additionally, a high CET1 ratio may indicate that a bank is taking a conservative approach to managing risk, which could mean slower growth or lower returns on equity. Conversely, a low CET1 ratio may suggest that a bank is taking on higher risks to achieve higher profits, which could lead to greater volatility and potential losses.

Challenges and Criticisms

While CET1 is a critical measure of financial strength, it is not without its limitations and challenges:

1. Complexity in Risk Weighting: Determining the risk weights for different assets can be subjective, and banks often use internal models to calculate RWAs. These models can vary significantly between institutions, making it difficult to compare CET1 ratios across banks.
2. Impact on Lending: Higher capital requirements can reduce a bank’s ability to lend, as they may need to hold more capital against certain assets. Critics argue that overly stringent CET1 requirements could constrain credit growth and economic expansion, especially in times of recovery.
3. Procyclicality: Capital requirements like CET1 can be procyclical, meaning they can exacerbate economic downturns. In a recession, as asset values fall and losses mount, banks may need to raise additional capital, potentially reducing lending when the economy needs it most.

The Bottom Line

Common Equity Tier 1 (CET1) is the most important metric for assessing a bank's financial stability and ability to absorb losses. It consists of the highest quality capital, including common shares and retained earnings, and is essential for meeting regulatory requirements. Introduced by the Basel III framework after the 2008 financial crisis, CET1 helps ensure that banks remain resilient during periods of economic stress. While it is a critical measure of strength, challenges like complexity in risk weighting and the potential impact on lending highlight the balance regulators must strike between stability and growth.