Loan portfolio profitability: Diversification and bundlingas structural levers
Banking segments
Fecha: julio 2026
Marta Alberni, Laura Ciriza and María Rodríguez
SEFO, Spanish and International Economic & Financial Outlook, V. 15 N.º 4 (July 2026)
As rate tailwinds fade, Spanish banks face the structural challenge of sustaining profitability without relying on net interest margin expansion. Loan portfolio composition proves central to this challenge. Banks with higher loan-to-asset ratios consistently generate stronger interest income, while holdings in fixed-income securities and interbank assets correlate negatively with yields. Within the loan book itself, segment diversification is a decisive differentiator: entities with greater exposure to business and consumer lending report higher loan yields than those concentrated in mortgages, reflecting the higher risk, shorter duration, and repricing flexibility of those segments. Given the structural weight of mortgage lending in Spanish bank portfolios, customer bundling emerges as a complementary lever. Banks with higher mortgage volumes show a strong positive correlation with off-balance sheet assets, and the resulting fee income offsets compressed interest margins on standardised products. Sustaining profitability ultimately requires balancing portfolio diversification with a shift toward customer-level profitability management, supported by analytical frameworks that link product mix to lifecycle value.