The country’s largest chains, Migros and Coop, have their own well-established bonus schemes — Cumulus and Supercard, respectively.

The more goods you purchase in one chain or another (as well as in many of their subsidiaries), the more points you accumulate, and the more benefits you will reap.

READ ALSO: How can Swiss loyalty programmes help you save money?

So far it sounds good, but new information published by Neue Zurcher Zeitung (NZZ) this weekend claims that both chains have been collecting information about customers and selling it to third parties.

What exactly does this data reveal about customers?

If you have a loyalty programme in one (or both) of these supermarkets, as most people in Switzerland do, you may be worried about your personal information no longer being protected.

The data sold to outside sources is anonymous, which means your name, address, credit card information, and other sensitive information. is not sold — at least according to both retailers.

On the other hand, purchasing habits, age, gender, and the region where each customer lives, constitute ‘open’information for many companies seeking to better target new client base.

According to NZZ, Coop has even developed and put into operation a centralised customer information system.

This means that everything sold in the supermarket, online, or in one of the many Coop subsidiaries such as Jumbo, Import Parfumerie, and Interdiscount, is registered in the database, and then sold to third parties.

As for Migros, its management admitted receiving money from suppliers in exchange for this type of customer information, though exact revenues that both retailers have gotten from these third-party sources is not known.

What do the two retail giants say about this practice?

Both justify it by saying data collected through their loyalty cards helps them to better understand their customers’ needs and adapt their advertising accordingly.

Migros and Coop also insist that he anonymised data they sell is no longer “customer information” from the legal point of view.

However, “studies have shown that we can quickly draw conclusions about people if we cross-reference anonymous data with other sources, such as cookies,” Lucien Jucker of the German-speaking consumer protection organisation told the NZZ.

The only way to avoid this trap, he said, is to give up the Cumulus or the Supercard and become a truly ‘anonymous’ shopper.

Up to you to decide whether you want to forego all the savings and other benefits of the loyalty programmes in order to protect your anonymity.