On August 30, 2026, VolRoc recorded 224,453 active prediction markets across Kalshi and Polymarket, holding $1.77B in combined open interest. Day over day, active markets fell 20.7% and open interest fell 11.6% (vs August 29, 2026). Politics & Elections was the largest domain by open interest (33%), ahead of Sports (24%); together they accounted for 57% of all open interest. Kalshi carried 72% of active markets and Polymarket 28%.
Deterministic · template v1 · 2026-08-30
As of 2026-08-30 · 00:00 UTC
Active Markets
224,453
00:00 UTC freeze
Open Interest
$1.77B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
24,924
with trading activity
Kalshi / Polymarket
72% / 28%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
126,686
Sports
38,643
Other
36,660
Politics & Elections
10,583
Entertainment & Culture
3,288
Crypto & Digital Assets
1,851
Technology & AI
1,789
Climate & Weather
1,366
Companies & Business
1,058
Economics & Inflation
992
World & Geopolitics
864
Monetary Policy
533
Science & Health
140
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 = 224,453.
Largest Kalshi Series
Cross-category multi-markets
126,686
Midterm control
1,207
Music — artist streams
750
Ncaafspread
707
U.S. House races
625
Nextteamnba
513
Ncaaftotal
385
Ncaafgame
371
Nflwins
363
Ncaafwins
345
Nflspread
325
—
288
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 30, 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 30, 2026.” https://volroc.ai/prediction-markets/2026-08-30/
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