O-SII Buffer

The O-SII buffer is a macroprudential policy instrument aiming at reducing moral hazard and strengthening the resilience of systemically important credit institutions.

In this context, moral hazard arises when a credit institution expects not to be let to fail given its systemic importance (“too big to fail”). An O-SII buffer limits excessive risk-taking by a systemically important credit institution through higher capital requirements, thus reducing moral hazard. Moreover, it cushions the systemic impact of misaligned incentives by strengthening the systemically important institution’s capital buffer to absorb potential losses and thus reduces contagion risk. 

The O-SII buffer consists of Common Equity Tier 1 (CET1) capital and its rate is set by the Bank of Greece at a level up to 3% of the total risk exposure amount on a consolidated, sub-consolidated or individual basis, as applicable, and is reviewed at least once a year. An O-SII buffer rate higher than 3% is subject to European Commission authorisation.

The Bank of Greece is also responsible for identifying, among credit institutions authorised in Greece, other systemically important institutions (O-SIIs). O-SIIs are identified on an annual basis so as to consider the application of an O-SII buffer. It should be noted that there are no global systemically important institutions (G-SIIs) in Greece.

The Bank of Greece has adopted the European Banking Authority (EBA) guidelines in relation to the assessment of O-SIIs (EBA/GL/2014/10). These guidelines lay down harmonised criteria, indicators, scoring methodology and thresholds, with a view to achieving convergence of national O-SII identification procedures, thus ensuring comparability, clarity and transparency in the assessment of systemically important institutions at EU level.

In accordance with this methodology, a score is calculated for each credit institution indicating its systemic importance based on specific criteria that relate to size, importance for the economy, complexity and interconnectedness of the institution with the financial system. These four criteria each consist of one or more mandatory indicators which are used as a minimum in the calculation of each credit institution’s score, expressed in basis points (bps). The 350 bps has been set as an indicative threshold. Institutions with a score equal to or higher than the threshold are identified as O-SIIs. The table below shows the mandatory indicators and relevant weights used for the scoring of O-SIIs in Greece. 

Table: Mandatory indicators for the scoring of O-SIIs in Greece





Total assets



Value of domestic payment transactions


Private sector deposits from depositors in the EU


Private sector loans to recipients in the EU


Complexity/ Cross-border activity

Value of OTC derivatives (notional)


Cross-jurisdictional liabilities


Cross-jurisdictional claims



Intra-financial system liabilities


Intra-financial system assets


Debt securities outstanding


Source: European Banking Authority (EBA) Guidelines on the criteria to determine the conditions of application of Article 131(3) of Directive 2013/36/EU (CRD) in relation to the assessment of other systemically important institutions (O-SIIs) (EBA/GL/2014/10).

In parallel, the European Central Bank (ECB) introduced a floor methodology for the calibration of the O-SII buffer for countries participating in the Single Supervisory Mechanism (SSM). This methodology forms part of the analysis which the ECB conducts when assessing the O-SII buffers set by national authorities in the SSM area.

Since 1 January 2016, the Bank of Greece has applied the above O-SII identification and calibration framework and the following credit institutions have been identified as O-SIIs: National Bank of Greece S.A., Piraeus Financial Holdings S.A., Alpha Services and Holdings S.A., and Eurobank Ergasias Services and Holdings S.A. The Bank of Greece decided to set the O-SII buffer at 0% for all O-SIIs for 2016-2018, 0.25% for 2019, 0.50% for 2020 and 2021, and 0.75% for 2022. The O-SII buffer rate is also imposed at solo basis on the following credit institutions: Alpha Bank S.A., Eurobank Ergasias S.A., National Bank of Greece S.A., and Piraeus Bank S.A. 


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