重新审视监管资本结构（英）

Revisiting theregulatorycapital stack Claudio Borio, Rodrigo Coelho, Fernando Restoy and NikolaTarashev November 2025 FSI Briefs are written by staff members of the Financial Stability Institute (FSI) of the Bank for InternationalSettlements (BIS), sometimes in cooperation with other experts. They are short notes on regulatory andsupervisory subjects of topical interest and are technical in character. The views expressed in thispublication are those of the authors and do not necessarily reflect the views of the BIS, its member centralbanks or the Basel-based standard-setting bodies. This publication is available on the BIS website (www.bis.org). To contact the BIS Global Media and PublicRelationsteam,pleaseemailmedia@bis.org.Youcansignupforemailalertsatwww.bis.org/emailalerts.htm. ©Bank for International Settlements 2025. All rights reserved. Brief excerpts may be reproduced ortranslated provided the source is stated. Revisiting the regulatory capital stack1, 2 Highlights •The post-Great Financial Crisis regulatory reforms have directly contributed to a more resilientfinancial system and supported sustainable growth, but some concrete aspects can be improved.•The complexity of the current capital framework and limitations in the loss-absorbing capacity ofsomeof its components can limit the effectiveness of bank regulation in achieving coremicroprudential, macroprudential and resolution objectives.•This paper discusses conceptually the capital stack – its components and their distinct roles. It thensuggests, at a technical level, how to simplify the current capital framework and how to enhance itseffectiveness in generating loss-absorbing resources while maintaining its stringency.•Ultimately, the aim of this paper is to provide an analytical reference for the ongoing debate onhow to improve the effectiveness and reduce the complexity of the current regulatory capital stack. 1.Introduction The capital stack is the bedrock of banking regulation, serving multiple policy objectives. From amicroprudential perspective, it seeks to safeguard the safety and soundness of individual banks. From amacroprudential standpoint, it strengthens the resilience of the financial system, moderates the amplitudeof the financial cycle and helps to reduce the likelihood that shocks propagate. In addition, parts of thecapital stack absorb losses to facilitate the orderly resolution of failing banks. Since the Great Financial Crisis (GFC), the capital – as well as liquidity – positions of banks haveimproved significantly, and the banking sector’s enhanced resilience has supported sustainable economicgrowth. The aftermath of the Covid-19 crisis is a testament to banks’ resilience. In contrast to 2008, whenbanks were the source of vulnerabilities, the Basel III reform underpinned their role as a shock absorberduring the pandemic (BCBS (2021)). In addition, assessments of the long-term effects indicate that greaterresilience did not come at the expense of banks’ cost of capital and that the reforms did not impair theaggregate supply of credit to the economy (BCBS (2022)). That said, a debate has emerged on possible ways to improve the current design of the regulatorycapital stack. While the available evidence does not suggest that this is an urgent task, there appears tobe scope to improve some technical aspects of the current framework. For one, the multifaceted nature of the capital stack introduces undesirable complexity. Banksmust comply with several interlocking requirements, including those for Common Equity Tier 1 (CET1)capital, Tier 1 capital, total capital, various regulatory buffers, total loss-absorbing capacity (TLAC) and theleverage ratio. To be sure, some of this complexity is necessary; but some is counterproductive andavoidable. In practice, assessing the relative stringency of these capital requirements can become quite difficult, and even just calculating them can become burdensome. The complexity thus creates challengesnot only for banks but also for investors, observers and even supervisors, potentially undermining theeffectiveness of the prudential framework. At the heart of these challenges is an imperfect alignmentbetween the various objectives of the framework and the elements of the capital stack. Moreover, and in part because of its complexity, the framework faces challenges in delivering onits core purpose of loss absorption. Notably, while a bank needs to meet several minimum requirementsto be considered viable, instruments eligible for some of these requirements need not improve the bank’sviability. Conversely, instruments that do underpin viability can also meet requirements for resolution,introducing possible inconsistencies in the framework. Further, while CET1 capital has been highly effectivein absorbing losses on a going-concern basis, Additional Tier 1 (AT1) instruments have exhibitedlimitations, notably in periods of financial stress. And “usable” buffers have proven insufficient, esp