On October 4, 2026, VolRoc recorded 380,621 active prediction markets across Kalshi and Polymarket, holding $1.24B in combined open interest. Day over day, active markets rose 3.0% and open interest fell 50.7% (vs October 3, 2026). Politics & Elections was the largest domain by open interest (23%), ahead of Sports (8%); together they accounted for 31% of all open interest. Kalshi carried 93% of active markets and Polymarket 7%.
Deterministic · template v1 · 2026-10-04
As of 2026-10-04 · 00:00 UTC
Active Markets
380,621
00:00 UTC freeze
Open Interest
$1.24B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
12,020
with trading activity
Kalshi / Polymarket
93% / 7%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
346,779
Sports
13,662
Other
9,567
Politics & Elections
6,669
Crypto & Digital Assets
1,190
Technology & AI
755
World & Geopolitics
666
Entertainment & Culture
362
Companies & Business
314
Economics & Inflation
286
Climate & Weather
194
Monetary Policy
129
Science & Health
48
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 = 380,621.
Largest Kalshi Series
Cross-category multi-markets
285,904
KXMVECROSSCATEGORY0
60,875
Nflrec
297
Nhlgoal
218
Nflrecyds
208
Nfltd
152
Nflrshyds
117
Nhltotal
95
Btcd
79
Mlbhrr
67
Nflrshatt
63
Mlbhit
62
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 4, 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 4, 2026.” https://volroc.ai/prediction-markets/2026-10-04/
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