Kalshi's category evolution is dramatic. During the 2024 election, politics consumed over 90% of all OI. Now it's roughly split between politics (~41%) and sports (~46%), with culture (~6%) and macro (~4%) filling the rest. From a single-category platform to a much more balanced mix.

> Polymarket also hit 95%+ politics during the 2024 election. But unlike Kalshi, it stayed politics-heavy at 54% today. Still, diversification is happening. Sports went from barely ~1% in early 2024 to ~21%, and crypto holds a steady ~13%. The category mix is broadening, especially after the December 2025 US re-entry.

> The category split reveals two completely different user bases. Kalshi's crypto OI share is just ~2%, Polymarket's is ~15% (reflecting its crypto-native origins). Sports is the inverse: Kalshi ~46% vs Polymarket ~21%. Same industry, but completely different user profiles. Mainstream sports bettors are flocking to Kalshi, while crypto-native users with political interests are concentrating on Polymarket.