Source: Messari; Compiled by: Jinse Finance
Kalshi's recent growth has been rapid and well-documented. Over the past six months, its monthly notional trading volume has increased by 775%, from $664.4 million in May to $5.81 billion in November.
During the same period, open interest (OI) increased by 266%, from $91.6 million on May 31 to $335.3 million on November 30.
Kalshi only surpassed Polymarket in weekly trading volume in August, but has maintained its lead ever since.
Over the past 14 weeks, Kalshi has held the top spot for 12 weeks. This string of leading positions is closely linked to a key factor: on August 19th, Kalshi partnered with Robinhood, allowing users to trade NFL and college football game results directly through Robinhood's prediction market hub. This partnership represents a breakthrough in two key areas. First, it increased engagement among non-crypto users, enabling them to trade prediction market results directly through their Robinhood accounts without any on-chain experience. Second, it provided US users with a legal and regulated way to trade sports event results through prediction markets, a service not offered by Polymarket at the time.

However, a more significant change occurred at the underlying level. The surge in trading volume was not partly driven by sporting events, but almost entirely by them. In November, 90.5% ($5.23 billion) of Kalshi's trading volume came from the sports market.
Open Interest (OI) shows a similar trend: as of November 30, 44.6% ($149.4 million) of OI came from the sports marketplace, making it the largest segment among the platform's two metrics. This in itself is neither good nor bad. The sports marketplace is deeply ingrained in American culture, and Kalshi earns commissions from marketplace orders, regardless of the marketplace's segment. However, sports trading is seasonal, with the biggest driver—American football—having the shortest peak season. Kalshi's explosive growth coincides with the peak of the football season, raising the question: can it maintain this momentum after the season ends? The team has begun expanding its business beyond the football field. On October 17th, Robinhood expanded Kalshi's prediction market offerings to include political and macroeconomic markets such as tariffs, Federal Reserve policy, and spending cuts. On December 3rd, CNN announced a partnership with Kalshi, integrating its prediction market into its newsroom; subsequently, CNBC made a similar announcement on December 4th. These were all correct moves. They broadened the scope of non-sports prediction markets available to users and increased exposure through mainstream media channels. CNN and CNBC, in particular, allowed Kalshi to reach audiences who might have never been exposed to prediction markets before. However, sports events still dominate to date. Whether this situation will change in 2026 depends on whether users can generate the same transaction volume in these new markets as they have in the football market. Kalshi's products are scaling up. But the next step is not just to continue growing, but to diversify across the industry.