Why Proportional Bank Regulation Is a Mapping Problem
This series examines how regulators design simplified rules for small and community banks, with the 2026 changes to the U.S. Community Bank Leverage Ratio (CBLR) as a concrete case. The central question is not whether a smaller bank deserves a smaller rulebook. It is whether each simplification is mapped to the bank’s actual activities and risks, bounded by eligibility conditions, and protected by safeguards that preserve resilience. That perspective helps readers judge what a proportional regime changes, what it leaves exposed, and what the available evidence does not yet show.
The distinction matters because banking rules do several jobs at once. They measure capital, constrain liquidity risk, limit concentration, inform supervisors and disclose information to markets. A rule that is unnecessarily complex for a genuinely simple institution can consume scarce resources without adding equivalent protection. But a rule that is merely removed may leave a risk unmeasured. Proportional regulation is therefore a design problem: fit the measurement and burden to the institution without confusing simplicity with safety.
The subject is the small-bank rulebook—and its mismatch
Small banks typically lend to households and small businesses, take deposits from local customers and operate within a narrower geographic and product range. Local ownership and specialized knowledge can make them important to communities that larger institutions serve less personally. Their business model can also diversify a banking system that might otherwise depend on a few large firms.
Large banks, by contrast, commonly serve a more diverse customer base, operate across national or international markets and combine lending with activities such as wealth management and trading. Their structures and risk-management systems are correspondingly more complex. A single regulatory framework can therefore impose very different costs on the two groups. A detailed risk-based capital calculation may be routine for a large institution but disproportionately burdensome for a small one.
That difference does not make the smaller institution uniformly safer. A locally focused bank may be less systemically central than a globally diversified bank, yet more exposed to a local recession, a narrow customer base or a concentrated loan book. Its funding may depend heavily on retail deposits from the same community that supplies its borrowers. The bank can be simple in structure while still being vulnerable to a shock that affects both sides of its balance sheet.
This combination creates the real policy tension. Regulators want to avoid imposing the full operational machinery built for complex, internationally active firms on banks that do not conduct those activities. At the same time, they cannot assume that a small balance sheet eliminates liquidity, concentration or governance problems. The subject is not “light regulation” in the abstract. It is the regulatory regime for a particular class of institutions whose advantages and vulnerabilities are both shaped by local scale.
Proportionality is a fit, not a discount
The Basel framework supplies a useful starting principle. Its core principles for effective banking supervision apply broadly, while the wider framework—largely designed for internationally active banks—can be tailored for other banks according to size, complexity and risk profile. The Basel Committee gives authorities room to make that judgment rather than prescribing one global definition of a small bank.
That discretion is important, but it also creates the central design challenge. Across the six jurisdictions reviewed by the Bank for International Settlements (BIS), asset size is the one criterion they all use, yet their thresholds differ substantially. Some use fixed asset limits; Brazil links its threshold to gross domestic product; the European Union and United Kingdom use averages over several years to reduce the effect of temporary fluctuations. Size is easy to observe, but it is only a proxy for the risks a rule is meant to control.
The BIS describes the governing objective as being “conservative yet simple.” In practical terms, a simpler rule should not be treated as a discount on resilience. It should be a different way of obtaining enough protection for an institution whose activities make the full rule unnecessary or poorly matched. That requires asking what information the original rule captures, which part of that information the simplified version gives up, and what boundary or safeguard compensates for the loss.
The logic can be represented as a chain rather than a list of exemptions:
The arrows do not mean that every jurisdiction uses the same sequence or the same thresholds. They show the relationship a coherent regime has to maintain. If a simplified capital measure ignores a type of exposure, eligibility may need to limit that exposure. If reporting is reduced, the retained data must still let supervisors see the risks that matter. If a bank grows or changes its activities, the regime needs a controlled way to reconsider its status.
The three questions every regime must answer
The first question is who qualifies? Size may be the entry point, but complexity and risk profile determine whether size is a sufficient guide. Jurisdictions in the BIS comparison use limits on trading-book exposures, derivatives, commodities, internal models, cross-border activity and off-balance-sheet exposures. These are not arbitrary hurdles. They can keep a bank from using a simple measurement regime while retaining activities whose risks that measurement captures poorly.
The second question is what changes? Proportionality can be applied to capital, leverage, liquidity, large-exposure limits, supervisory reporting or market disclosure. It need not be applied in the same way across all of them. One jurisdiction may replace risk-based capital with a higher leverage ratio. Another may retain risk-based capital but simplify market-risk calculations or combine several buffers. A third may leave capital requirements largely unchanged and reduce reporting instead.
The third question is how is resilience protected? A higher leverage requirement can compensate in part for the loss of risk-sensitive calculations, but the answer depends on how the exposure measure is defined. A liquidity proxy can reduce calculation burden, but it still has to serve a stable-funding or short-term-liquidity purpose. A shorter disclosure template can be proportionate only if it retains information that is material to supervisors or market users. The safeguard must be matched to the risk being simplified; there is no generic “small-bank adjustment” that settles every function.
This is why eligibility and requirements cannot be designed independently. If a regulator removes market-risk capital requirements, a cap on trading activity may be necessary. If a regime exempts an institution from a liquidity ratio, its eligibility conditions may need to identify banks with a low liquidity-risk profile, adequate funding or satisfactory supervisory assessments. The more a regime streamlines, the more important it becomes to identify precisely what it has chosen not to measure.
CBLR makes the logic concrete
The U.S. CBLR illustrates this relationship without representing the whole field. On April 23, 2026, the Federal Reserve, Federal Deposit Insurance Corporation and Office of the Comptroller of the Currency announced a final rule modifying the community bank leverage-ratio framework. The rule lowers the required community bank leverage ratio from 9 percent to 8 percent and extends the grace period for a bank that temporarily falls out of compliance from two quarters to four quarters. The changes take effect July 1, 2026.
The framework allows an eligible community bank to use a relatively simple leverage measure instead of calculating and reporting risk-based capital ratios. The agencies nevertheless describe the requirement as one that continues to promote safety and soundness, and they note that the applicable leverage ratio remains significantly higher than the leverage standard otherwise applicable to community banks. The design therefore combines operational relief with a more conservative threshold than a general leverage minimum would provide.
The change also shows why a number cannot be interpreted by itself. The BIS comparison notes that the U.S. leverage calculation excludes off-balance-sheet exposures, while Switzerland’s comparable small-bank approach includes them. Two ratios with the same percentage can therefore place different demands on a bank, because their denominators measure different exposures. The U.S. framework also uses eligibility conditions that limit which community banks can use the option. The ratio is one part of a map, not a universal score for bank safety.
The longer grace period has a different function from the lower threshold. A lower threshold can make the simplified option available to more banks. A longer transition period can reduce the chance that a temporary change in a bank’s condition immediately forces reclassification. Neither change, on the evidence available here, tells us whether participating banks will lend more, become more profitable or remain safer over time. They alter the legal and operational design; their downstream effects require separate evidence.
What this evidence can—and cannot—tell us
The BIS paper is a comparative stock-take of small-bank regimes in Brazil, Switzerland, China, the European Union, the United Kingdom and the United States. It shows that authorities have made different choices about the same design problem. Some use a higher leverage ratio; some simplify selected risk-based-capital components; some focus proportionality on liquidity, reporting or disclosure. The comparison is valuable because it reveals the variables that matter, not because it identifies one winning template.
The available evidence is strongest on rules, stated policy objectives and design mechanisms. It is not an impact evaluation. The sources do not establish how a particular regime changes local credit supply, profitability, failure rates or systemic stability. Nor does the Federal Reserve’s press release provide the full legal text or every detailed eligibility formula behind the CBLR change. Those limits are part of the subject: a defensible analysis must distinguish an announced rule from its later effects.
The next question follows directly from the mapping model. Before a bank can receive a simpler rule, an authority has to decide whether the bank is simple enough for that rule—and what happens when its size, activities or condition change. Smallness is the starting signal, not the conclusion.