Basel III

Regulatory & Compliance · intermediate · CC-BY-4.0

Basel III is a comprehensive set of international banking regulatory standards developed by the Basel Committee on Banking Supervision (BCBS) in response to the 2007–2009 global financial crisis, establishing minimum capital requirements, leverage limits, and liquidity standards designed to improve the resilience of the global banking system.

Key takeaways

• Basel III requires banks to hold higher and better-quality capital — Common Equity Tier 1 (CET1) must be at least 4.5% of risk-weighted assets, with additional buffers raising the effective minimum to 7%.
• The framework introduced two liquidity standards: the Liquidity Coverage Ratio (LCR), requiring sufficient high-quality liquid assets to cover 30 days of net cash outflows, and the Net Stable Funding Ratio (NSFR), targeting stable longer-term funding.
• A leverage ratio — Tier 1 capital divided by total exposure — was introduced as a non-risk-based backstop, set at a minimum of 3% (higher for G-SIBs).
• Global Systemically Important Banks (G-SIBs) face additional capital surcharges of 1–3.5%, implemented on a tiered basis according to systemic importance scores.
• Basel III significantly increased the cost of balance sheet capacity for banks, reducing prime brokerage leverage, repo book capacity, and market-making activity — with direct consequences for hedge fund financing.

Explanation

Basel III emerged from the recognition that the pre-crisis banking system was dangerously undercapitalized, excessively leveraged, and dependent on short-term wholesale funding that evaporated in a stress scenario. The Basel I and II frameworks had allowed banks to accumulate enormous exposures against thin capital cushions, often through off-balance-sheet vehicles and complex securitization structures that received favorable regulatory capital treatment.

The capital framework under Basel III consists of three tiers. Common Equity Tier 1 (CET1) — comprising retained earnings, paid-in capital, and other comprehensive income — is the highest quality capital and must constitute at least 4.5% of risk-weighted assets (RWA). Additional Tier 1 (AT1) instruments (principally contingent convertible bonds, or 'CoCos') and Tier 2 capital (subordinated debt) can supplement CET1, bringing the total minimum capital requirement to 8%. On top of the minimum, banks must maintain a Capital Conservation Buffer of 2.5% (comprised entirely of CET1), bringing the effective CET1 floor to 7%. Countercyclical Capital Buffers of up to 2.5% can be imposed by national regulators during periods of excessive credit growth.

The liquidity standards address two distinct horizons. The LCR requires banks to hold a stock of High Quality Liquid Assets (HQLA — predominantly government bonds and central bank reserves) sufficient to survive a 30-day acute stress scenario as defined by regulatory prescribed outflow rates. The NSFR, which became effective in 2018, requires that a bank's available stable funding (ASF) equal or exceed its required stable funding (RSF) over a one-year horizon, penalizing reliance on short-dated wholesale funding to finance long-dated illiquid assets.

For hedge funds, Basel III's most direct impact has been through the prime brokerage and repo markets. Bank prime brokers, constrained by leverage ratios and NSFR requirements, significantly reduced the size of their balance sheets dedicated to financing hedge fund positions. This manifested as higher margin rates, tighter rehypothecation limits, and reduced availability of financing for less liquid assets. The post-Basel III era saw a bifurcation of prime brokerage — larger hedge funds with institutional relationships retained favorable financing terms, while smaller funds faced materially higher costs of leverage.

Formula

CET1 Ratio = CET1 Capital / Risk-Weighted Assets >= 7% (including conservation buffer)
LCR = HQLA / Net Cash Outflows over 30 days >= 100%
NSFR = Available Stable Funding / Required Stable Funding >= 100%

Example

Consider a major U.S. bank with $1 trillion in risk-weighted assets. Under Basel III, it must hold at minimum $70 billion in CET1 capital (7% of RWA), compared to perhaps $25–30 billion under Basel II. If the bank earns a 12% return on equity (ROE) on its prime brokerage book, forcing it to hold more than double the capital against those assets roughly halves the RWA-normalized profitability of that business. The bank responds by charging hedge fund clients higher financing spreads (increasing borrow rates from SOFR+50bps to SOFR+120bps) and reducing exposure to illiquid collateral. A mid-size macro hedge fund relying on 5:1 leverage to execute its strategy may find its borrowing costs increasing by 70 basis points annually — directly reducing net returns by the same amount on the leveraged portion of the book.

Related terms

Basis Central Bank Cftc Registration Equity Fbar Financial Crisis Finra Floor Hedge Fund Leverage Liquidity Margin