On July 25, 2026, VolRoc recorded 235,254 active prediction markets across Kalshi and Polymarket, holding $1.80B in combined open interest. Day over day, active markets rose 99.8% and open interest rose 25.4% (vs July 24, 2026). Sports was the largest domain by open interest (50%), ahead of Politics & Elections (26%); together they accounted for 76% of all open interest. Kalshi carried 83% of active markets and Polymarket 17%.
Deterministic · template v1 · 2026-07-25
As of 2026-07-25 · 00:00 UTC
Active Markets
235,254
00:00 UTC freeze
Open Interest
$1.80B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
20,696
with trading activity
Kalshi / Polymarket
83% / 17%
by active-market count
Domain Composition — 12 domains
Sports
165,057
Other
27,084
Mixed / Multi-category
26,949
Politics & Elections
6,475
Entertainment & Culture
2,699
Crypto & Digital Assets
1,830
Companies & Business
1,199
Climate & Weather
1,111
Technology & AI
960
Economics & Inflation
865
World & Geopolitics
484
Monetary Policy
459
Science & Health
82
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 = 235,254.
Largest Kalshi Series
Sports — multi-game parlays
140,589
Cross-category multi-markets
26,949
Midterm control
900
Music — artist streams
767
U.S. House races
595
Nextteamnba
472
Mlbhr
271
NFL — next team moves
255
Nflwins
237
Nextteammlb
229
Mlbhrr
202
Flprimary
195
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 July 25, 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 — July 25, 2026.” https://volroc.ai/prediction-markets/2026-07-25/
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