Some 5,000 people demonstrated Saturday in the northwestern Spanish town of Sanjenjo in protest against some complex bank products known as preferred securities, which are often no longer worth the savings they invested in them.

The protesters, mostly middle-aged and retired, demanded that the Novagalicia Bank return the savings they plunged into those products.

Coming from all parts of Galicia, the province where Sanjenjo is located, and amid the noise of sirens and whistles, the marchers chanted slogans against those responsible for the savings banks that were swallowed up to form the Novagalicia Bank.

They also threw eggs against a Novagalicia branch office during a march that surprised the summer vacationers in this coastal town.

The demonstrators stopped for a few minutes on their march to air their anger before the summer home of Spain's conservative Prime Minister Mariano Rajoy.

According to data from the ADICAE bank users association, to which thousands affected by these products belong, in Spain there are more than a million families that are "victims" of these preferred securities, which had total deposits of some 30 billion euros ($37 billion) in May 2011, but have since dwindled through a process of swaps with other financial entities to about 11.3 billion euros ($13.9 billion), according to the regulatory National Stock Market Commission, or CNMV.

Preferred securities have no expiration date and pay a dividend based on how much profit the bank makes, and can only be cashed in using one of two methods: at a rate offered by the bank on its own terms, or sold on a secondary market, which could bring in less than the original investment.

The high interest rates paid during the boom years have now largely descended to zero.

Consumers say that the bank never informed them of these characteristics and now denies them the sales orders needed to put their preferred securities on the market, a situation they call the "Spanish corral."