Spanish banks, which are mainly retail lenders, tend to benefit more from higher interest rates than their euro zone peers. They have had higher returns on mortgage loans, largely tied to floating rates, offseting a 3.4% decline in overall loans last year while keeping a lid on rates for savers.

As of February, Spanish banks offered an average return on one-year household deposits of 2.37%, compared to 3.2% in the euro zone as a whole.