On August 12, 2026, VolRoc recorded 209,350 active prediction markets across Kalshi and Polymarket, holding $1.53B in combined open interest. Day over day, active markets rose 35.4% and open interest rose 10.9% (vs August 11, 2026). Sports was the largest domain by open interest (34%), ahead of Politics & Elections (33%); together they accounted for 67% of all open interest. Kalshi carried 94% of active markets and Polymarket 6%.
Deterministic · template v1 · 2026-08-12
As of 2026-08-12 · 00:00 UTC
Active Markets
209,350
00:00 UTC freeze
Open Interest
$1.53B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
17,214
with trading activity
Kalshi / Polymarket
94% / 6%
by active-market count
Domain Composition — 12 domains
Sports
98,173
Mixed / Multi-category
80,092
Other
17,086
Politics & Elections
6,247
Entertainment & Culture
2,677
Crypto & Digital Assets
1,411
Economics & Inflation
1,011
Technology & AI
908
Companies & Business
778
Monetary Policy
403
World & Geopolitics
297
Climate & Weather
191
Science & Health
76
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 = 209,350.
Largest Kalshi Series
Sports — multi-game parlays
85,491
Cross-category multi-markets
80,092
Midterm control
1,050
Music — artist streams
741
U.S. House races
606
Nextteamnba
503
Nflwins
304
Nfltotal
258
Nflspread
241
Mlbhr
231
NFL — next team moves
229
Ncaafwins
228
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 August 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 — August 12, 2026.” https://volroc.ai/prediction-markets/2026-08-12/
Get the daily statistics
A short daily read on the prediction-market universe across Kalshi and Polymarket.
Join the list →