The Bank of Spain said it fined both CaixaBank SA and Banco Bilbao Vizcaya Argentaria SA for infringing rules concerning the sale of mortgages.
The regulator said it had fined CaixaBank €3.6 million for a "very serious infringement" with regards to the rules on early mortgage repayments and a further €1.2 million for a "serious infringement" in providing precontractual and contractual information and the way in which it had calculated interest rates.
BBVA was fined a total of €2.7 million for two "serious infringements" with regards to early repayments and interest rate calculations, among other things.
Spanish banks have been sharply criticized by consumer groups for mistreating customers, and the country has seen several mis-selling scandals.
The Bank of Spain made the decision to fine the lenders in late November but made the announcement Dec. 28.