On October 10, 2026, VolRoc recorded 351,854 active prediction markets across Kalshi and Polymarket, holding $2.48B in combined open interest. Day over day, active markets fell 23.7% and open interest fell 7.4% (vs October 9, 2026). Politics & Elections was the largest domain by open interest (22%), ahead of Sports (16%); together they accounted for 39% of all open interest. Kalshi carried 93% of active markets and Polymarket 7%.
Deterministic · template v1 · 2026-10-10
As of 2026-10-10 · 00:00 UTC
Active Markets
351,854
00:00 UTC freeze
Open Interest
$2.48B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
23,663
with trading activity
Kalshi / Polymarket
93% / 7%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
282,045
Other
27,064
Sports
25,522
Politics & Elections
8,654
Entertainment & Culture
2,920
Crypto & Digital Assets
1,333
Economics & Inflation
990
Companies & Business
878
Technology & AI
839
World & Geopolitics
699
Monetary Policy
513
Climate & Weather
316
Science & Health
81
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 = 351,854.
Largest Kalshi Series
Cross-category multi-markets
225,844
KXMVECROSSCATEGORY0
56,201
Midterm control
1,853
Votegeneral
1,578
Ncaafspread
790
U.S. House races
677
Music — artist streams
580
Ncaaftotal
466
Midtermvoteturn
452
Nfltd
448
Nextteamnba
427
Nflwins
411
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 October 10, 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 — October 10, 2026.” https://volroc.ai/prediction-markets/2026-10-10/
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