On August 20, 2026, VolRoc recorded 183,183 active prediction markets across Kalshi and Polymarket, holding $1.49B in combined open interest. Day over day, active markets fell 3.5% and open interest fell 3.9% (vs August 19, 2026). Politics & Elections was the largest domain by open interest (33%), ahead of Sports (23%); together they accounted for 56% of all open interest. Kalshi carried 93% of active markets and Polymarket 7%.
Deterministic · template v1 · 2026-08-20
As of 2026-08-20 · 00:00 UTC
Active Markets
183,183
00:00 UTC freeze
Open Interest
$1.49B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
17,743
with trading activity
Kalshi / Polymarket
93% / 7%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
134,618
Other
18,508
Sports
16,305
Politics & Elections
6,018
Entertainment & Culture
2,717
Crypto & Digital Assets
1,516
Technology & AI
893
Economics & Inflation
861
Companies & Business
737
Monetary Policy
417
World & Geopolitics
311
Climate & Weather
206
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 = 183,183.
Largest Kalshi Series
Cross-category multi-markets
134,618
Sports — multi-game parlays
2,932
Midterm control
1,116
Music — artist streams
775
U.S. House races
612
Nextteamnba
508
Nflwins
347
Primary vote shares
327
Nflspread
310
Ncaafwins
271
Nfltotal
261
Mlbhit
258
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 20, 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 20, 2026.” https://volroc.ai/prediction-markets/2026-08-20/
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