Systemically Important Bank Capital Coverage / 系统重要性银行资本覆盖

Definition

Systemically important bank capital coverage is a prudential requirement that a banking parent fund specified subsidiary exposures with common equity capable of absorbing losses, reducing the risk that a thinly capitalized parent must sell assets or seek state support when a foreign unit fails.

Current Synthesis

The Swiss proposal described by 商业就是这样 targets the mismatch between a globally large banking group and a comparatively small home-state backstop. Requiring UBS / 瑞银 to cover 90% of the carrying value of foreign-subsidiary holdings with common-equity Tier 1 capital would strengthen loss absorption, but it would also retain funds that shareholders might otherwise receive and could encourage asset sales or a smaller balance sheet. The rule is therefore both a resilience mechanism and a distributional choice.

Key Claims

• Parent-level equity coverage protects against losses passing upward from foreign subsidiaries into a weakly capitalized home entity.
• Common equity remains usable in banking operations but cannot simultaneously serve as distributable dividends or buybacks.
• A rule becomes more economically consequential when one bank is exceptionally large relative to its home country’s economy.
• Higher capital can be met through new equity, retained earnings, lower distributions, asset sales, or balance-sheet contraction, each assigning cost differently.
• Cross-country similarity in prudential aims does not imply identical coverage ratios or calculations.

Evidence

• Mechanism and scale: 商业小样51 | 什么，瑞银要把总部搬离瑞士？ explains the proposed 90% coverage rule against UBS’s reported $1.7tn asset base and foreign-subsidiary structure.
• Cost channels: 商业小样51 | 什么，瑞银要把总部搬离瑞士？ gives about $16bn as the revised additional-capital estimate and identifies issuance, reduced distributions, and asset sales as responses.
• Policy origin: 商业小样51 | 什么，瑞银要把总部搬离瑞士？ connects the proposal to the 2023 Credit Suisse rescue and the larger combined UBS.

Counterevidence & Qualifications

The proposal is unfinished, and the episode does not supply the full draft law, transition period, deductions, group accounting, stress assumptions, or official cross-country comparison. More capital can reduce shareholder returns without proving that a rule is excessive; conversely, a high ratio does not by itself guarantee resolvability or prevent a run. The 90%, $16bn, $17.7bn, asset, and GDP figures remain source-scoped and time-sensitive.

What Changed

• Added the parent-versus-foreign-subsidiary capital mismatch as a distinct systemic-risk mechanism.
• Connected prudential resilience directly to dividends, buybacks, asset sales, and bank scale.
• Added the home-state capacity problem created when a rescued bank becomes larger after consolidation.

Related Concepts

• Banking Loss Allocation Politics - capital requirements decide who pre-funds the cost of resilience.
• Moral Hazard Contagion Tradeoff - stronger buffers respond to the rescue tension between preventing contagion and rewarding risk.
• Deposit Guarantee Crisis Response - adjacent emergency backstop that becomes relevant when private loss absorption proves insufficient.
• Accelerated Bank Runs - confidence shocks can consume time faster than capital and resolution actions can be arranged.
• 总部迁移监管杠杆 - domicile change can be invoked as a response to costly home-state rules.