The Basel III Endgame Debate: Industry Impact

Introduction

The US Basel III Endgame rule is the single most consequential regulatory development in banking since Dodd-Frank, and as of early 2026, it remains unfinalized. The original July 2023 proposal would have raised capital requirements by 19% for the largest US banks, fundamentally altering lending capacity, trading economics, and M&A feasibility. The industry mounted an unprecedented lobbying campaign that forced a major regulatory retreat, and a change in presidential administration has shifted the trajectory further toward a capital-neutral outcome. For FIG bankers, Basel III Endgame is not just a regulatory topic; it is the variable that determines how much excess capital banks can deploy for acquisitions, buybacks, and growth over the next decade.

On July 27, 2023, the OCC, FDIC, and Federal Reserve jointly proposed sweeping revisions to large bank capital requirements. The proposal would have increased capital requirements by an aggregate 19% for GSIBs, 16% on average across banks with more than $100 billion in assets, and raised total risk-weighted assets by approximately 20% across affected institutions. The rule replaced the internal ratings-based (IRB) approach for credit risk with an expanded standardized approach, introduced the Fundamental Review of the Trading Book (FRTB) for market risk, overhauled operational risk measurement, and imposed a standardized output floor at 72.5% of RWA (phased in from 50% starting 2025 to 72.5% by 2030).

The industry response was immediate and aggressive. Jamie Dimon (JPMorgan Chase) and Brian Moynihan (Bank of America) testified before the Senate Banking Committee in December 2023, arguing the rule would "curtail lending and weaken bank balance sheets" despite "zero evidence that large US banks are undercapitalized today." The Bank Policy Institute retained conservative litigator Eugene Scalia to prepare litigation on grounds including arbitrary and capricious rulemaking and violation of the major questions doctrine. PwC estimated the proposal could reduce US GDP growth by up to 56 basis points annually, approximately $42 billion in lost output per year.

Output Floor

The output floor is a Basel III mechanism designed to limit how much benefit banks can derive from internal risk models. It sets a minimum: a bank's total risk-weighted assets under internal models cannot fall below 72.5% of what the standardized approach would produce. If a bank's internal models calculate RWA of $500 billion but the standardized approach yields $800 billion, the floor forces the bank to use at least $580 billion (72.5% of $800 billion). The floor's purpose is to prevent internal models from producing unrealistically low capital requirements, but its effect is to increase capital requirements for banks that have historically used more favorable internal approaches, particularly for mortgage lending, trading, and operational risk.

On September 10, 2024, Fed Vice Chair for Supervision Michael Barr announced "broadly and materially" revised rules that cut the capital impact from 19% to approximately 9% for the largest banks, a reduction of more than half. The revised proposal eliminated the 20-percentage-point risk-weight add-on for single-family mortgages (a major pressure point from the housing industry), removed the requirement to deduct mortgage servicing rights from CET1 capital, and largely exempted banks with $100 billion to $250 billion in assets from the core changes. Barr pledged a new 60-day comment period.

While the US stalls, other jurisdictions have moved forward, creating a fragmented global landscape. The EU adopted CRR3/CRD6 effective January 1, 2025, though it delayed FRTB market risk application to January 1, 2027 and pushed the output floor phase-in to full implementation by January 1, 2030. The EU retained regional adjustments including SME and infrastructure calibrations and broad CVA exemptions for derivatives with non-financial corporates. The UK PRA published final Basel 3.1 rules in January 2026 with a go-live date of January 1, 2027, also targeting full output floor implementation by 2030.

This divergence creates competitive implications for global banks. US GSIBs face uncertainty in capital planning while European and British peers have clear timelines. The EU explicitly cited US implementation delays as a reason for postponing its own FRTB go-live, acknowledging that uneven implementation creates level-playing-field concerns.

The Basel III Endgame uncertainty has paradoxically both constrained and accelerated bank M&A. On the constraining side, banks cannot precisely calculate pro forma CET1 ratios for potential acquisitions when the denominator (risk-weighted assets) may change significantly depending on the final rule. Capital buffers maintained for "regulatory uncertainty" represent idle capital that cannot be deployed for deals or returned to shareholders.

On the accelerating side, the expectation of a capital-neutral or even capital-releasing outcome under the current administration has emboldened deal activity. The 2024-2025 bank consolidation wave occurred partly because acquirers concluded that final capital requirements would be manageable. Banks like Fifth Third, Huntington, and Capital One structured their acquisitions with sufficient capital cushion to absorb a reasonable range of outcomes.