On August 25, 2026, VolRoc recorded 188,864 active prediction markets across Kalshi and Polymarket, holding $1.68B in combined open interest. Day over day, active markets rose 20.6% and open interest rose 14.9% (vs August 24, 2026). Politics & Elections was the largest domain by open interest (34%), ahead of Sports (21%); together they accounted for 55% of all open interest. Kalshi carried 70% of active markets and Polymarket 30%.
Deterministic · template v1 · 2026-08-25
As of 2026-08-25 · 00:00 UTC
Active Markets
188,864
00:00 UTC freeze
Open Interest
$1.68B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
23,221
with trading activity
Kalshi / Polymarket
70% / 30%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
98,808
Other
34,413
Sports
33,611
Politics & Elections
10,432
Entertainment & Culture
2,979
Crypto & Digital Assets
1,936
Technology & AI
1,747
Climate & Weather
1,459
Economics & Inflation
1,005
Companies & Business
985
World & Geopolitics
892
Monetary Policy
488
Science & Health
109
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 = 188,864.
Largest Kalshi Series
Cross-category multi-markets
98,808
Midterm control
1,178
—
1,174
Music — artist streams
765
U.S. House races
614
Nextteamnba
508
Primary vote shares
364
Nflwins
357
Ncaafwins
304
Nflspread
266
Nfltotal
235
NFL — next team moves
230
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 25, 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 25, 2026.” https://volroc.ai/prediction-markets/2026-08-25/
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