On October 13, 2026, VolRoc recorded 287,624 active prediction markets across Kalshi and Polymarket, holding $934.8M in combined open interest. Day over day, active markets fell 4.6% and open interest rose 13.3% (vs October 12, 2026). Politics & Elections was the largest domain by open interest (29%), ahead of Sports (10%); together they accounted for 39% of all open interest. Kalshi carried 91% of active markets and Polymarket 9%.
Deterministic · template v1 · 2026-10-13
As of 2026-10-13 · 00:00 UTC
Active Markets
287,624
00:00 UTC freeze
Open Interest
$934.8M
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
10,052
with trading activity
Kalshi / Polymarket
91% / 9%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
258,131
Sports
11,420
Other
9,042
Politics & Elections
5,189
Crypto & Digital Assets
1,182
Technology & AI
754
World & Geopolitics
666
Entertainment & Culture
346
Companies & Business
310
Economics & Inflation
250
Climate & Weather
158
Monetary Policy
128
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 = 287,624.
Largest Kalshi Series
Cross-category multi-markets
247,884
KXMVECROSSCATEGORY0
10,247
Ncaafspread
231
Ncaaftotal
150
Btcd
115
Mlbhrr
100
Nflrec
95
Nflspread
78
Mlbhit
77
Nbaspread
68
Nhlgoal
66
Rain
66
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 13, 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 13, 2026.” https://volroc.ai/prediction-markets/2026-10-13/
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