On July 30, 2026, VolRoc recorded 143,065 active prediction markets across Kalshi and Polymarket, holding $1.35B in combined open interest. Day over day, active markets fell 19.2% and open interest fell 4.2% (vs July 29, 2026). Sports was the largest domain by open interest (36%), ahead of Politics & Elections (36%); together they accounted for 72% of all open interest. Kalshi carried 78% of active markets and Polymarket 22%.
Deterministic · template v1 · 2026-07-30
As of 2026-07-30 · 00:00 UTC
Active Markets
143,065
00:00 UTC freeze
Open Interest
$1.35B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
17,965
with trading activity
Kalshi / Polymarket
78% / 22%
by active-market count
Domain Composition — 12 domains
Sports
86,455
Other
24,098
Mixed / Multi-category
17,224
Politics & Elections
6,602
Entertainment & Culture
2,630
Crypto & Digital Assets
1,563
Companies & Business
1,237
Technology & AI
1,191
Economics & Inflation
969
World & Geopolitics
428
Monetary Policy
368
Climate & Weather
208
Science & Health
92
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 = 143,065.
Largest Kalshi Series
Sports — multi-game parlays
65,301
Cross-category multi-markets
17,224
Midterm control
936
Music — artist streams
759
U.S. House races
601
Nextteamnba
480
Nflwins
259
NFL — next team moves
257
Nextteammlb
236
Flprimary
203
Mlbseasonhr
161
Ncaafwins
161
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 30, 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 30, 2026.” https://volroc.ai/prediction-markets/2026-07-30/
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