Are Spain's Property Website Algorithms Pushing Up Prices? Congress Wants Answers

Could the Search Engines Be Part of the Problem?

Spain's property market has seen prices rise 12.9% year-on-year — the fourth highest in the EU — driven by supply shortages, tourist apartments and an influx of wealthy foreign buyers. But some experts now claim the very search engines used to find homes could be making things worse.

Reporting in the Spanish press suggests that the algorithms used by Idealista and Fotocasa — Spain's two biggest property portals — could encourage unfair competition, favouring corporate networks and large-scale property owners over small private individuals, and pushing prices up overall.

Listings 44% Above Actual Value?

Left-wing news outlet El Salto claims property listings on these websites show prices up to 44% higher than the average values actually declared before a notary.

Critics say the algorithms display prices significantly above the notarial valuation — the actual economic value of a property — and then use that inflated, standardised price as the basis for future listings. The result is a feedback loop that pushes prices ever higher.

How the Algorithm Works

According to Más Madrid MP Tesh Sidi, who tabled a motion in Congress:

"Idealista's artificial intelligence algorithm is not updated according to actual sales figures because the government publishes them months later. Therefore, the algorithm sets the sales figure on the portal as the base price and does not adjust it over time. When another user goes to buy a flat in that same area, the price at which user X bought it is set as the baseline."

El Salto also claims the sites weigh data by number of listings rather than geographical area, creating significant price gaps.

Congress Wants Answers

Far-left coalition partner Sumar has put a motion before Congress calling for:

• Representatives from both Idealista and Fotocasa to appear before the Committee on Economy, Trade and Digital Transformation
• A new body within Spain's National Commission for Markets and Competition (CNMC) to monitor the effects of AI on the housing market
• Greater transparency and regulation of property platform algorithms

Is It Legal?

Professor Borja Adsuara from the Universidad Complutense de Madrid argues that when platform filters serve the platform's interests rather than the user's, "we are no longer talking about a recommendation, but about manipulation."

He points to the EU Digital Services Act, which bans such practices. Users can also pay for enhanced photos, professional photography and valuation services — all of which boost an ad's ranking and drive more interactions.

What This Means for Buyers

For expats and anyone searching for property in Spain, the takeaway is clear: don't take the asking price on Idealista or Fotocasa as gospel. Cross-reference with notarial values, ask your gestor to check comparable sales data, and don't be afraid to negotiate. The listed price may be significantly above what properties in the area are actually selling for.

This article is based on reporting from The Local Spain, published April 10, 2026. This article is for informational purposes only and does not constitute property or financial advice.