On October 12, 2026, VolRoc recorded 301,337 active prediction markets across Kalshi and Polymarket, holding $825.1M in combined open interest. Day over day, active markets fell 24.0% and open interest fell 33.4% (vs October 11, 2026). Politics & Elections was the largest domain by open interest (32%), ahead of Sports (10%); together they accounted for 42% of all open interest. Kalshi carried 92% of active markets and Polymarket 8%.
Deterministic · template v1 · 2026-10-12
As of 2026-10-12 · 00:00 UTC
Active Markets
301,337
00:00 UTC freeze
Open Interest
$825.1M
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
7,904
with trading activity
Kalshi / Polymarket
92% / 8%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
274,103
Sports
10,135
Other
8,179
Politics & Elections
5,149
Crypto & Digital Assets
1,169
Technology & AI
754
World & Geopolitics
666
Entertainment & Culture
343
Companies & Business
310
Economics & Inflation
229
Monetary Policy
128
Climate & Weather
124
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 = 301,337.
Largest Kalshi Series
Cross-category multi-markets
238,958
KXMVECROSSCATEGORY0
35,145
Nhlgoal
108
Btcd
101
Ncaafspread
84
Nhlpts
55
Nflrecyds
54
Nbaspread
47
Ncaaftotal
45
Ethd
43
Nbatotal
39
Nhlast
39
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 12, 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 12, 2026.” https://volroc.ai/prediction-markets/2026-10-12/
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