On October 3, 2026, VolRoc recorded 369,400 active prediction markets across Kalshi and Polymarket, holding $2.52B in combined open interest. Day over day, active markets rose 7.8% and open interest rose 9.8% (vs October 2, 2026). Politics & Elections was the largest domain by open interest (23%), ahead of Sports (16%); together they accounted for 39% of all open interest. Kalshi carried 92% of active markets and Polymarket 8%.
Deterministic · template v1 · 2026-10-03
As of 2026-10-03 · 00:00 UTC
Active Markets
369,400
00:00 UTC freeze
Open Interest
$2.52B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
24,927
with trading activity
Kalshi / Polymarket
92% / 8%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
297,450
Sports
26,951
Other
26,451
Politics & Elections
10,027
Entertainment & Culture
2,946
Crypto & Digital Assets
1,357
Economics & Inflation
984
Technology & AI
840
Companies & Business
811
World & Geopolitics
696
Monetary Policy
502
Climate & Weather
305
Science & Health
80
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 = 369,400.
Largest Kalshi Series
Cross-category multi-markets
231,654
KXMVECROSSCATEGORY0
65,796
Midterm control
1,655
Votegeneral
1,450
Ncaafspread
814
U.S. House races
671
Music — artist streams
604
Ncaaftotal
540
Nfltd
466
Ncaafwins
437
Nflwins
435
Nextteamnba
426
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 3, 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 3, 2026.” https://volroc.ai/prediction-markets/2026-10-03/
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