The Bank of Spain has updated its designation of Other Systemically Important Institutions (O-SIIs) for 2026 and set the corresponding macroprudential capital buffer rates. The list is unchanged from 2025 and continues to cover Banco Santander, Banco Bilbao Vizcaya Argentaria, CaixaBank and Banco de Sabadell at consolidated level. O-SII identification follows the European Banking Authority indicator-based methodology and applies an automatic designation threshold of 350 basis points. The Common Equity Tier 1 (CET1) buffer rates, expressed as a percentage of consolidated risk-weighted assets, are unchanged for Banco Santander (1.25%), CaixaBank (0.5%) and Banco de Sabadell (0.25%), while Banco Bilbao Vizcaya Argentaria’s buffer falls from 1.0% to 0.75% due to its lower systemic importance score placing it in a lower bucket; for Santander, the applicable requirement for 2026 is 1.25% as the higher of its O-SII and G-SII buffers. The decision has been notified to the European Central Bank, the European Systemic Risk Board and Spain’s macroprudential authority (AMCESFI), which issued a favourable opinion.