On October 9, 2026, VolRoc recorded 461,168 active prediction markets across Kalshi and Polymarket, holding $2.68B in combined open interest. Day over day, active markets rose 33.7% and open interest rose 12.6% (vs October 8, 2026). Politics & Elections was the largest domain by open interest (21%), ahead of Sports (15%); together they accounted for 36% of all open interest. Kalshi carried 94% of active markets and Polymarket 6%.
Deterministic · template v1 · 2026-10-09
As of 2026-10-09 · 00:00 UTC
Active Markets
461,168
00:00 UTC freeze
Open Interest
$2.68B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
22,769
with trading activity
Kalshi / Polymarket
94% / 6%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
391,894
Other
27,215
Sports
24,772
Politics & Elections
8,613
Entertainment & Culture
2,907
Crypto & Digital Assets
1,406
Economics & Inflation
1,025
Companies & Business
874
Technology & AI
839
World & Geopolitics
699
Monetary Policy
511
Climate & Weather
332
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 = 461,168.
Largest Kalshi Series
Cross-category multi-markets
334,806
KXMVECROSSCATEGORY0
57,088
Midterm control
1,830
Votegeneral
1,554
Ncaafspread
695
U.S. House races
673
Music — artist streams
585
Midtermvoteturn
439
Nextteamnba
427
Nflwins
413
Ncaafwins
408
Ncaaftotal
407
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 9, 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 9, 2026.” https://volroc.ai/prediction-markets/2026-10-09/
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