Prediction market operators took the world by storm during the FIFA World Cup — then they faded under the summer sun.
With an expected surge in activity expected once the NFL season and midterm elections begin, prediction markets are experiencing a rare decline in popularity after more than a year of extraordinary growth. And amid that, Kalshi is strengthening its hold on a dominant share of the trading market.
Prediction market search volume in freefall
According to Google Trends, Kalshi and Polymarket both peaked in search popularity on matchdays during the World Cup. The term “prediction market” set its five-year high during the first week of the competition and its daily high on July 19, the day that Spain beat Argentina in the Final, 1-0.
Google Trends showed a search index of 100, an all-time high, during the week of June 7-13, 2026. That was over six times higher than the search index of 16 reported during the last completed week, Aug. 9-15.
Similarly, the term “prediction markets” reached an index of 100 during the week of June 28-July 4. Aug. 9-15 only produced a search index of 28, roughly 3.5 times lower.
Both indexes are well below the immediate pre-tournament figures. For the search term “prediction market,” Google Trends didn’t record an index lower than 17 since Dec. 21-27, 2025.
This is a stark contrast to the unprecedented popularity prediction markets enjoyed during the World Cup. Interest in the index hit 85 during June 14–20, 92 during June 28-July 4, 82 during July 5-11, and 57 from July 12-18.
Trading data has also followed a similar trend, much to the disappointment of leading operators.
Kalshi taking Polymarket’s audience
Prediction market cash trading volume reached $14.8 billion in June and $17.3 billion in July, according to DefiLlama. As of Monday, Aug. 16, the volume had dropped to $7.8 billion, setting a monthly trajectory of $14.3 billion, down approximately 17% month-over-month.
Cash trading volume is not the same as notional trading volume. Cash trading measures the actual money exchanged in a transaction, whereas notional volume measures all underlying value. Notional trading volume is typically much larger; in the case of Kalshi, its 30-day notional volume ($36.7 billion) is more than three times higher than its cash volume ($11 billion).
Even as trading volume has dropped, Kalshi has strengthened its lead over its leading competitor, Polymarket. In June, the platforms produced $9.4 billion and $4.3 billion in cash trading volume, separating themselves by a factor of 2.2. That increased to 3.4 in July based on $12.4 billion from Kalshi and $3.7 billion from Polymarket, and increased again to 4.9 halfway through August, according to the $5.8 billion produced by Kalshi and $1.2 billion by Polymarket.
All of this comes during a wave of resurgent state action. Gaming regulators and officials in multiple jurisdictions have found their most legal success in recent weeks, many of them benefitting from court judgments denying preliminary injunction requests from Kalshi and other prediction market operators.
These decisions do not mean that states have the ultimate legal authority over prediction markets, but that they cannot be preemptively prevented from applying enforcement measures.
The Trade Handle Prediction Markets Take
Although prediction markets insist they are not sports betting, they are experiencing the same “dead period” that occurs when most professional and amateur sports are out of action. The September return of the NFL, the most popular league in America, will inevitably result in a surge in activity, given that the last NFL season is what helped put the national spotlight on prediction markets.