Banco Santander, S.A. delivered resilient Q1 2026 results, with revenues up 4% YoY but bottom-line missing consensus and shares underperforming the market. SAN's earnings growth outlook is modest, with mixed NII prospects—European rate tailwinds offset by Brazilian headwinds—and fee growth likely to remain single-digit. Operational efficiency remains the core driver, with the ONE Transformation program targeting a cost-to-income ratio drop from 45% (2025) to 36% (2028).