On July 17, 2026, VolRoc recorded 135,261 active prediction markets across Kalshi and Polymarket, holding $1.61B in combined open interest. Day over day, active markets rose 45.7% and open interest rose 15.3% (vs July 16, 2026). Sports was the largest domain by open interest (44%), ahead of Politics & Elections (28%); together they accounted for 72% of all open interest. Kalshi carried 75% of active markets and Polymarket 25%.
Deterministic · template v1 · 2026-07-17
As of 2026-07-17 · 00:00 UTC
Active Markets
135,261
00:00 UTC freeze
Open Interest
$1.61B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
17,011
with trading activity
Kalshi / Polymarket
75% / 25%
by active-market count
Domain Composition — 12 domains
Sports
86,827
Other
23,487
Mixed / Multi-category
11,175
Politics & Elections
6,320
Entertainment & Culture
2,549
Crypto & Digital Assets
1,595
Companies & Business
877
Economics & Inflation
778
Technology & AI
493
World & Geopolitics
476
Monetary Policy
423
Climate & Weather
146
Science & Health
115
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 = 135,261.
Largest Kalshi Series
Sports — multi-game parlays
63,457
Cross-category multi-markets
11,175
Midterm control
854
Music — artist streams
774
U.S. House races
590
Nextteamnba
439
Pgatour
279
NFL — next team moves
254
Nextteammlb
221
Nflwins
206
KXPGATOP20
201
Wcaward
197
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 17, 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 17, 2026.” https://volroc.ai/prediction-markets/2026-07-17/
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