The cajas were founded as a charity initiative 200 years ago, principally to hold grain that could be distributed to farmers in times of scarcity. The lenders then could hardly have suspected that they would still be operating in the 21st century and that their risk models would be barely more sophisticated.

In recent years, cajas started bypassing the Bank of Spain's conservative investment rules, buying complex derivative products, backed by grain and other commodities, as well as by toxic real-estate loans.