The notices came after regulators failed to notify the companies through known foreign addresses.
Kalshi and Polymarket currently dominate prediction markets’ trading activity. Over the past 30 days, Kalshi recorded roughly $5.9 billion in trading volume while Polymarket processed about $3.8 billion, according to DeFiLlama data.
Combined, the two platforms represent nearly 88% of the roughly $11 billion in trading volume among the sector’s top markets during the period.
The move sees Spain join a growing number of jurisdictions targeting prediction markets as regulators debate whether the products should fall under gambling or financial market rules.
Indonesia blocked Polymarket earlier this week under online gambling restrictions, as did India. Other countries including Taiwan, Thailand China, and Japan have restricted the platform, while Ukraine blocked it with no legal way for it to come back.
Polymarket’s list of blocked countries also includes Belgium, Australia, France, the U.K., and Germany. The platform is relaunching in the U.S.
Kalshi followed a different regulatory route in the U.S., where it operates under oversight from the Commodity Futures Trading Commission (CFTC). Still, it’s been under fire.
Spanish authorities said unlicensed operators may lack safeguards such as identity checks, protections for minors and systems for self-excluded gamblers.