On August 15, 2026, VolRoc recorded 188,804 active prediction markets across Kalshi and Polymarket, holding $1.52B in combined open interest. Day over day, active markets rose 28.2% and open interest rose 7.1% (vs August 14, 2026). Politics & Elections was the largest domain by open interest (34%), ahead of Sports (33%); together they accounted for 67% of all open interest. Kalshi carried 93% of active markets and Polymarket 7%.
Deterministic · template v1 · 2026-08-15
As of 2026-08-15 · 00:00 UTC
Active Markets
188,804
00:00 UTC freeze
Open Interest
$1.52B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
16,715
with trading activity
Kalshi / Polymarket
93% / 7%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
80,155
Sports
77,556
Other
17,441
Politics & Elections
6,222
Entertainment & Culture
2,697
Crypto & Digital Assets
1,323
Technology & AI
893
Economics & Inflation
812
Companies & Business
709
Monetary Policy
409
World & Geopolitics
310
Climate & Weather
201
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 = 188,804.
Largest Kalshi Series
Cross-category multi-markets
80,155
Sports — multi-game parlays
64,661
Midterm control
1,073
Music — artist streams
734
U.S. House races
612
Nextteamnba
506
Nflwins
321
Nflspread
297
Ncaafwins
243
Mlbhr
238
Nfltotal
237
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 15, 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 15, 2026.” https://volroc.ai/prediction-markets/2026-08-15/
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