This paper investigates how the European Union and Spanish changes to the regulation and the declaration of some unfair terms in mortgage loan agreements have affected the valuation of the Spanish banking industry. This paper has a dual legal and economic focus, and could consequently be of interest not only to financial institutions but also to the administrator of justice, which oversees the correct functioning of the financial system and the protection of consumer rights, in this case, mortgage holders. The empirical analysis was carried out using a sample of Spanish companies composed of 11 financial institutions that are listed, or have been listed, on the Madrid stock exchange and 24 non-financial companies listed on the IBEX-35 index. The period analysed was from December 2009 to March 2019. One of the main conclusions was the observation that, in general, the abnormal negative returns of financial institutions are greater when dealing with a decision from the Court of Justice of the European Union rather than from the Spanish Supreme Court. The events referred to as unfair terms that have had the most impact as a whole on the returns of shareholders were, because of their impact of the valuation of financial institutions, in order of importance, those relating to default interest charges, followed by rounding up, and, in last place, the unfair terms of floor clauses, mortgage constitution expenses and multi-currency loans.

本文研究了欧盟和西班牙对法规的更改以及抵押贷款协议中某些不公平条款的声明如何影响西班牙银行业的估值。本文具有法律和经济双重关注，因此不仅可能对金融机构而且对司法行政官都有好处，司法行政官负责监督金融系统的正常运作和对消费者权益的保护，在这种情况下为抵押持有人。使用西班牙公司样本进行了实证分析，该公司由11家在马德里证券交易所上市或已经上市的金融机构和24家在IBEX-35指数中上市的非金融公司组成。分析的期间为2009年12月至2019年3月。主要结论之一是观察到，通常来说，在处理欧洲联盟法院而不是西班牙最高法院的裁决时，金融机构的异常负收益更大。从整体上讲，对股东回报产生最大影响的被称为不公平条款的事件是由于其对金融机构估值的影响，按重要性排序的，与违约利息费用有关，然后进行四舍五入，最后还有地板条款，抵押宪法规定的费用和多币种贷款的不公平条款。