On August 8, 2026, VolRoc recorded 203,220 active prediction markets across Kalshi and Polymarket, holding $1.51B in combined open interest. Day over day, active markets rose 51.9% and open interest rose 13.7% (vs August 7, 2026). Sports was the largest domain by open interest (37%), ahead of Politics & Elections (33%); together they accounted for 70% of all open interest. Kalshi carried 93% of active markets and Polymarket 7%.
Deterministic · template v1 · 2026-08-08
As of 2026-08-08 · 00:00 UTC
Active Markets
203,220
00:00 UTC freeze
Open Interest
$1.51B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
17,344
with trading activity
Kalshi / Polymarket
93% / 7%
by active-market count
Domain Composition — 12 domains
Sports
110,264
Mixed / Multi-category
61,344
Other
17,639
Politics & Elections
6,280
Entertainment & Culture
2,668
Crypto & Digital Assets
1,341
Economics & Inflation
964
Technology & AI
949
Companies & Business
734
Monetary Policy
399
World & Geopolitics
372
Climate & Weather
190
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 = 203,220.
Largest Kalshi Series
Sports — multi-game parlays
96,908
Cross-category multi-markets
61,344
Midterm control
1,008
Music — artist streams
743
U.S. House races
606
Nextteamnba
495
Nflwins
289
Mlbhr
276
Mlbhrr
248
Mlbhit
234
NFL — next team moves
227
Ncaafwins
209
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 8, 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 8, 2026.” https://volroc.ai/prediction-markets/2026-08-08/
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