The European Central Bank published a Working Paper, “A structural model of capital buffer usability”, which develops a non-linear structural model to examine when banks will actually draw down regulatory capital buffers in stress. The paper finds that even very small stigma costs associated with breaching the capital buffer requirement (CBR) can materially constrain buffer usability, prompting banks to deleverage to avoid falling below the CBR and weakening the ability of non-releasable buffers to sustain loan supply when losses occur. The views are those of the authors and do not necessarily reflect those of the ECB. The model distinguishes a minimum capital requirement that cannot be breached (breach leads to resolution/liquidation with costs) from a CBR that can be breached but triggers stigma costs meant to capture consequences such as increased supervisory scrutiny, capital conservation plans and payout restrictions. Calibrated to euro area data, the analysis suggests that in “normal” times stigma of around 0.5–3 basis points is sufficient to induce banks to meet the CBR, raising capital ratios by 0.5–1.3 percentage points versus a minimum-only regime, lowering failure probabilities by 1.25–2.0 percentage points, and reducing aggregate loans by only 1–13 basis points. In “bad” times when banks are loss-making and equity-constrained, the same low stigma range is sufficient to eliminate equilibria where banks use the CBR, with banks instead deleveraging materially (illustratively up to around 10%) to continue meeting the CBR; equilibria with such usability constraints can be supported by higher “individual” stigma costs of roughly 10–30 basis points when a single bank breaches the CBR. The paper’s policy discussion argues that while a structural, non-releasable CBR can raise resilience in normal conditions, it is unlikely to fully achieve the macro-stabilisation aim of supporting loan supply during losses if stigma leads to buffer usability constraints. It suggests reconsidering the composition of the CBR to increase the share of releasable buffers, while noting that further analysis would be needed.
European Central Bank 2026-02-16
European Central Bank working paper models capital buffer usability and finds stigma can drive deleveraging instead of buffer use
The European Central Bank's Working Paper, “A structural model of capital buffer usability,” finds that even small stigma costs can limit banks' use of regulatory capital buffers during stress, leading to deleveraging to avoid breaching the capital buffer requirement (CBR). The paper suggests that while a non-releasable CBR can enhance resilience in normal conditions, it may not support loan supply during losses if stigma constrains buffer usability, recommending reconsidering the CBR's composition to increase releasable buffers.