Banking Regulation
Leverage Ratio
The 3% non-risk-weighted floor that catches the gaming the risk-weighted system cannot
The Basel III leverage ratio caps a bank's balance sheet at 33 times its Tier 1 capital — Tier 1 / total exposure ≥ 3%. No risk weights. No internal models. The deliberate brute-force complement to the risk-weighted capital ratios. G-SIBs face 4-5% in many jurisdictions; Lehman 2008 ran 2%.
- FormulaTier 1 / Total exposure ≥ 3% (Basel III)
- TypeNon-risk-weighted floor (no RWA in denominator)
- G-SIB requirement+1.5× G-SIB surcharge: typically 4.0–5.0%
- US implementationSupplementary Leverage Ratio (SLR) · eSLR 5–6% for G-SIBs
- Lehman 2008~2% effective ratio — below the floor that did not yet exist
- Phased inDisclosed 2015 · binding 2018 (Basel III timeline)
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The formula and what it deliberately excludes
The Basel III leverage ratio is structurally trivial:
Leverage ratio = Tier 1 capital / Total exposure ≥ 3%
Tier 1 capital = CET1 + AT1 (Common equity + qualifying contingent convertibles)
Total exposure = On-balance-sheet assets
+ Derivative exposures (SA-CCR)
+ Securities-financing transactions
+ Off-balance-sheet items (at prescribed CCFs)The denominator deliberately omits the entire risk-weighting machinery of the capital adequacy framework. A Treasury bill, a residential mortgage, a junk-rated corporate loan, and a subprime CDO all count one-for-one in total exposure — and each requires a minimum 3 cents of Tier 1 capital per dollar of exposure. The crudity is the entire point.
What the leverage ratio does include is everything off-balance-sheet that could become balance-sheet exposure in a stress: derivative counterparty exposures (under the SA-CCR), securities-financing transactions (repos, sec-lending, prime brokerage), and unfunded commitments (lines of credit, letters of credit) at prescribed conversion factors. The 2014 Basel revision specifically tightened these inclusion rules after early implementations let banks understate exposure by netting too aggressively.
Why risk weights weren't enough
The historical motivation comes directly from 2007-2008. Under Basel II, banks could assign internal-model risk weights that, with supervisor blessing, produced capital requirements that turned out to be wildly inadequate:
- OECD sovereigns at 0%. Including Greek government bonds before the 2010-2012 sovereign debt crisis. A bank holding €10bn of Greek bonds carried zero capital against them under Basel II — and watched a 70% haircut materialise in 2012.
- AAA-rated subprime CDOs at 20%. The "supersenior" tranches of subprime mortgage-backed CDOs received an investment-grade-or-better risk weight under Basel II. Banks held them on trading books with 1.6% capital against assets that subsequently lost most of their value in 2007-2008.
- Off-balance-sheet conduits. ABCP conduits and SIVs (structured investment vehicles) carried minimal capital under Basel II because their commitments had low conversion factors. Citigroup brought $80bn of SIV assets back onto its balance sheet in late 2007.
- Lehman's Tier 1 ratio. 11% in 2007 — well above any requirement of the day. The same balance sheet, on a pure-equity-to-assets basis, was 3-4% — and on a Basel III leverage-ratio basis, about 2%.
The Basel Committee's working group on capital concluded in 2010 that the risk-weighted ratios had failed in three ways: weights were wrong, internal models were too easy to manipulate, and off-balance-sheet exposures were not captured. A non-risk-weighted floor solved all three problems at once. The 3% level was chosen as a backstop that would have bound on the most leveraged investment banks but not on traditional commercial banks — about 33:1 maximum leverage on Tier 1.
Worked example: where the leverage ratio bites
Consider two stylised banks, each with $5bn of Tier 1 capital:
| Bank A (commercial) | Bank B (repo dealer) | |
|---|---|---|
| Tier 1 capital | $5bn | $5bn |
| Mortgages (50% RWA weight) | $30bn → $15bn RWA | $0 |
| Corporate loans (100% weight) | $15bn → $15bn RWA | $0 |
| Reverse repo, Treasury collateral (0% weight) | $10bn → $0bn RWA | $140bn → $0bn RWA |
| Total assets | $55bn | $140bn |
| Total RWA | $30bn | $0bn (plus small SA-CCR add-on) |
| Tier 1 / RWA (risk-weighted) | 16.7% | Undefined (very large) |
| Tier 1 / total exposure (leverage) | 9.1% | 3.6% |
| Binding constraint | Risk-weighted (16.7% > 6%, leverage 9% > 3% — both loose) | Leverage (3.6% — close to 3% floor) |
Bank A is constrained by the risk-weighted minimum and has lots of room on the leverage ratio. Bank B holds nothing but ostensibly zero-risk Treasury repo — the risk-weighted system says it can scale infinitely on $5bn of equity. The leverage ratio caps that at 33× ($165bn), and Bank B is operating near the limit. This is exactly the scenario the leverage ratio was designed to catch. Empirically, the largest US repo dealers and custody banks (JPMorgan trading book, Goldman Sachs, BNY Mellon, State Street) bind on SLR rather than risk-weighted ratios.
Leverage ratio vs other Basel III ratios
| Ratio | Numerator | Denominator | Minimum | What it catches |
|---|---|---|---|---|
| CET1 ratio | Common Equity Tier 1 | Risk-weighted assets | 4.5% + 2.5% buffer = 7% | Highest-quality loss absorption |
| Tier 1 ratio | CET1 + AT1 | Risk-weighted assets | 6% | Going-concern capital |
| Total capital ratio | Tier 1 + Tier 2 | Risk-weighted assets | 8% | Total loss-absorbing capital |
| Leverage ratio | Tier 1 | Total exposure (unweighted) | 3% | Risk-weight gaming |
| LCR | HQLA | 30-day net cash outflows | 100% | Short-term liquidity |
| NSFR | Available stable funding | Required stable funding | 100% | Long-term funding mismatch |
| SLR (US) | Tier 1 | Total leverage exposure | 3% (eSLR 5-6% G-SIB) | US implementation of Basel III leverage |
The leverage ratio's unique feature is that it is the only Basel III capital ratio whose denominator does not depend on risk modelling. The other three capital ratios all share the RWA denominator and differ only in what counts as eligible capital. A bank can satisfy CET1, Tier 1, and Total Capital ratios simultaneously while violating the leverage ratio — and that is exactly when the leverage ratio is doing useful work.
From Glass-Steagall to Basel III
Simple, non-risk-weighted leverage limits are old. US banking law from the early 20th century imposed a maximum 10:1 leverage ratio on national banks. The 1991 FDIC Improvement Act introduced Prompt Corrective Action thresholds explicitly based on a "leverage ratio" — Tier 1 to average total assets — at 5% (well capitalised) and 3% (adequately capitalised). The international Basel framework, however, did not adopt a leverage ratio until 2010, in part because European regulators (which had no comparable national-level leverage rule) resisted what they saw as a crude US import.
The 2008 crisis ended the resistance. Under Basel III, the leverage ratio entered as a Pillar 2 monitoring tool in 2013, became Pillar 3 disclosed in 2015, and became a Pillar 1 binding minimum in January 2018. The 2017 finalisation (informally Basel IV) added the G-SIB leverage buffer — 1.5 times the G-SIB risk-weighted surcharge. For JPMorgan at the top of the G-SIB list with a 2.5% RWA surcharge, the leverage ratio requirement becomes 3% + 1.5 × 2.5% = 6.75%.
The US Supplementary Leverage Ratio
The US implementation — the Supplementary Leverage Ratio — applies to banks with $250bn+ in consolidated assets at 3% Tier 1 / total leverage exposure. The enhanced SLR adds 200bp at the bank holding company level (5%) and 300bp at the insured depository subsidiary (6%) for US G-SIBs. The eSLR was finalised in 2014 and has been politically contested ever since.
The September 2019 repo-rate spike — overnight Treasury repo rates briefly hit 10% — was widely attributed to dealer banks reducing repo activity to economise on SLR exposure. The Fed responded with $200bn+ in overnight repo operations and ultimately resumed Treasury purchases. In Q2 2020, in response to COVID-driven balance-sheet expansion, the Fed temporarily excluded US Treasuries and central-bank reserves from the SLR denominator for bank holding companies. The exclusion expired in March 2021, sparking the same constraint to re-bind under different conditions. The political question of whether to permanently exclude Treasuries and reserves remained unresolved through the 2024-2025 Basel III Endgame negotiations.
Pitfalls and ongoing debates
- Crudity invites wrong incentives. If 3% is binding regardless of asset risk, a bank has economic motivation to fill exposure with the highest-yielding assets within the constraint. Critics (Hellwig, Admati) argue this is an argument for raising the floor to 10-20% rather than abandoning it.
- Off-balance-sheet measurement is approximation. The SA-CCR add-on for derivatives is a simplification; netting rules are jurisdiction-specific; the right exposure number for an exotic derivative depends on assumptions the standardised approach cannot capture cleanly.
- Treasury and reserve treatment is politically unstable. Excluding sovereign collateral from the denominator turns the leverage ratio back into a risk-weighted-lite construct. The temporary 2020 exclusion and its expiration revealed how sensitive G-SIB compliance is to a single decision on a single exposure class.
- SVB and the 2023 regional-bank crisis. Silicon Valley Bank sat below the US $250bn SLR threshold and was not subject to the binding leverage ratio. Its 2022-2023 balance sheet, with $211bn assets and $16bn Tier 1, produced an unweighted ratio around 7.6% — superficially comfortable. The actual problem was duration risk and rapid deposit flight, neither of which the leverage ratio directly addresses.
- Capital quality of the numerator. If a bank's Tier 1 includes AT1 contingent convertibles that fail to convert in stress (Credit Suisse, March 2023), the published leverage ratio overstates loss-absorbing capacity. The CET1-only leverage ratio (more conservative, less commonly reported) avoids this issue.
- Internal-model recapture via different routes. If a bank cannot game risk weights, it can still game the denominator: synthetic securitisations transfer risk off-balance-sheet but reduce both RWA and total exposure measures in ways supervisors have repeatedly tightened against. Regulatory cat-and-mouse continues.
Frequently asked questions
What is the Basel III leverage ratio?
The Basel III leverage ratio requires a bank's Tier 1 capital to be at least 3% of total exposure — on-balance-sheet assets plus off-balance-sheet items (derivatives, securities-financing transactions, and a portion of unfunded commitments) — with no risk weighting at all. It is a deliberate non-risk-weighted floor that ignores the model-based RWA system. The motivation is that risk-weighted ratios can be gamed by assigning low weights to assets that turn out to be risky. G-SIBs face higher requirements: 1.5 times their G-SIB capital surcharge added on top, so a 2.5% G-SIB faces a 4.25% leverage ratio.
Why a non-risk-weighted ratio when Basel already has risk-weighted ones?
Because risk weights are gameable. Under Basel II, a bank using internal models could assign a 20% risk weight to AAA-rated subprime CDO tranches, and a 0% weight to OECD sovereign debt (including Greek debt before 2010). The risk-weighted ratio claimed those banks were safe even when their pure-equity-to-assets ratio said otherwise. Lehman Brothers in 2007 reported a Tier 1 risk-weighted ratio of 11% — well above the 6% requirement — while running 30 times leverage on a roughly 4% pure-equity base. The 2008 crisis was, in part, the failure of the risk-weighted system. The leverage ratio is a brute-force backstop: regardless of how clever your risk weights are, you cannot have more than 33 times Tier 1 capital in total exposure.
What counts as "total exposure" in the denominator?
Three categories, each with prescribed measurement rules. (1) On-balance-sheet exposures: at their accounting value, with limited netting allowed. (2) Derivative exposures: using the standardised approach for counterparty credit risk (SA-CCR) — current exposure plus a potential-future-exposure add-on; netting allowed under master agreements. (3) Securities-financing transactions (repos, securities lending): gross plus an SFT add-on for counterparty credit risk. (4) Off-balance-sheet items: undrawn commitments at credit-conversion factors of 10-100% depending on commitment type. The whole thing is calculated quarterly and disclosed publicly under Basel III Pillar 3.
How is the US Supplementary Leverage Ratio (SLR) different?
The Supplementary Leverage Ratio is the US implementation of the Basel III leverage ratio for the largest banks. It applies to banks with $250bn+ in consolidated assets and requires Tier 1 / total leverage exposure ≥ 3%. On top of that, US G-SIBs face an enhanced SLR (eSLR) of 5% at the bank holding company level and 6% at the insured-depository-subsidiary level. Federal Reserve repo-market volatility in September 2019 was partly attributed to dealer banks reducing repo activity to economise on SLR — leading to the temporary Q2 2020 exclusion of Treasuries and central-bank reserves from the denominator, which was allowed to expire in March 2021. The treatment of Treasury exposures in the SLR remained politically contested through 2024-2025.
What was Lehman Brothers' leverage ratio in 2008?
Lehman's official Tier 1 risk-weighted ratio in 2007 was 11% — looking very strong. Its underlying ratio of common shareholders' equity to total assets was approximately 3% to 4%, putting it at 25-30 times leverage on the simplest measure. The Basel III leverage ratio, applied retrospectively to Lehman's 2007 balance sheet (with the SA-CCR derivatives add-on), would have been roughly 2%, well below the 3% floor that did not yet exist. Bear Stearns, Merrill Lynch, and Morgan Stanley were all in the same neighbourhood. The 3% floor was specifically calibrated to make those numbers retroactively non-compliant — Basel III's lesson learned from 2008. Note: Lehman's "official" headline GAAP leverage was 30:1, which under generous accounting assumptions corresponds to about 3% — but that excluded off-balance-sheet items the leverage ratio captures.
Why is 3% the chosen floor — and why higher for G-SIBs?
The 3% floor was calibrated by the Basel Committee in 2014-2017 to be consistent with the historical relationship between Tier 1 capital and risk-weighted assets at well-capitalised banks. At a typical RWA-to-assets ratio of 40-60%, the 3% non-risk-weighted floor binds roughly when the risk-weighted ratio would be 5-7.5% — slightly below the 6% Tier 1 minimum, leaving the risk-weighted ratio as the binding constraint for normal banks and the leverage ratio as the binding constraint only for very-low-risk-weight portfolios (sovereign-heavy, mortgage-heavy). The G-SIB surcharge — 1.5 times the capital G-SIB surcharge — applies because the systemic externalities of too-big-to-fail banks justify additional non-risk-weighted backup.
What types of banks bind on leverage rather than risk-weighted ratios?
Banks with very-low-risk-weighted books. Three types in particular: (1) Repo dealers — JPMorgan, Goldman Sachs, Deutsche Bank trading desks — whose balance sheets are dominated by short-dated reverse repo with Treasury collateral (near-zero risk weights). (2) Sovereign-heavy banks — many European banks under home-country zero-risk-weight rules. (3) Custody banks — BNY Mellon, State Street, Northern Trust — whose books are mostly low-risk-weight assets. For each, the risk-weighted minimum is trivial to satisfy; the leverage ratio is the binding constraint. Custody banks reduced repo activity and pushed clients away in 2019-2020 partly to manage SLR, contributing to repo-market dysfunction.
Is the leverage ratio actually the most effective Basel III tool?
Many post-2008 reformers argue it is. Andy Haldane (then-Bank of England chief economist) wrote in 2012 that the leverage ratio's simplicity made it "arguably the most effective ratio". Anat Admati and Martin Hellwig (2013, The Bankers' New Clothes) argue all risk-weighted ratios are gameable and only a 20-30% leverage requirement would be safe. The counter-argument is that crude ratios produce wrong incentives — banks shift toward riskier assets within whatever exposure budget the ratio allows. The Basel III architecture takes the eclectic position: keep both, make the tighter constraint bind, force banks to satisfy whichever rule has bite. The 2023 regional-bank crisis (SVB, Signature) was, in part, an episode where the leverage ratio's effective protection was diluted by US Basel III tailoring rules below the $250bn threshold.