On July 12, 2026, VolRoc recorded 331,532 active prediction markets across Kalshi and Polymarket, holding $2.25B in combined open interest. Day over day, active markets rose 33.6% and open interest rose 17.1% (vs July 11, 2026). Sports was the largest domain by open interest (51%), ahead of Politics & Elections (20%); together they accounted for 71% of all open interest. Kalshi carried 89% of active markets and Polymarket 11%.
Deterministic · template v1 · 2026-07-12
As of 2026-07-12 · 00:00 UTC
Active Markets
331,532
00:00 UTC freeze
Open Interest
$2.25B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
21,175
with trading activity
Kalshi / Polymarket
89% / 11%
by active-market count
Domain Composition — 12 domains
Sports
245,833
Mixed / Multi-category
45,767
Other
24,246
Politics & Elections
6,281
Entertainment & Culture
2,698
Crypto & Digital Assets
1,987
Climate & Weather
1,186
Companies & Business
1,096
Economics & Inflation
942
Technology & AI
494
World & Geopolitics
452
Monetary Policy
429
Science & Health
121
Venue-agnostic subject taxonomy from Kalshi series prefixes and
Polymarket title keywords. A residual Other bucket is reported honestly.
Yes-price across both venues, 10 buckets from 0 to 100. n = 331,532.
Largest Kalshi Series
Sports — multi-game parlays
222,283
Cross-category multi-markets
45,767
Midterm control
836
Music — artist streams
789
U.S. House races
589
Nextteamnba
437
Pgatour
310
NFL — next team moves
254
Nextteammlb
219
Mlbhr
206
Nflwins
201
Flprimary
189
Kalshi market families (Polymarket is not series-structured).
About & Citation
This is the fixed-hour (00:00 UTC) state of every active market on
Kalshi and Polymarket for July 12, 2026. The live
Observatory
shows the current diurnal value; this record is immutable. Open interest combines Kalshi
open interest with Polymarket USD liquidity as comparable USD magnitudes. Sources: Kalshi, Polymarket.
How to cite
“VolRoc Prediction Market Archive — July 12, 2026.” https://volroc.ai/prediction-markets/2026-07-12/
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