On June 21, 2026, VolRoc recorded 1,959 active prediction markets across Kalshi and Polymarket, holding $810.9M in combined open interest. Day over day, active markets fell 99.0% and open interest fell 65.4% (vs June 20, 2026). Sports was the largest domain by open interest (73%), ahead of Politics & Elections (24%); together they accounted for 97% of all open interest. Kalshi carried 6% of active markets and Polymarket 94%.
Deterministic · template v1 · 2026-06-21
As of 2026-06-21 · 00:00 UTC
Active Markets
1,959
00:00 UTC freeze
Open Interest
$810.9M
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
1,233
with trading activity
Kalshi / Polymarket
6% / 94%
by active-market count
Domain Composition — 10 domains
Politics & Elections
817
Other
357
Crypto & Digital Assets
285
Sports
190
Companies & Business
109
Technology & AI
88
World & Geopolitics
56
Entertainment & Culture
28
Monetary Policy
15
Economics & Inflation
12
Science & Health
2
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 = 1,959.
Largest Kalshi Series
Btcd
64
Sold
23
Ethd
21
Xrpd
13
KXETH15M
1
KXSOL15M
1
KXBTC15M
1
KXXRP15M
1
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 June 21, 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 — June 21, 2026.” https://volroc.ai/prediction-markets/2026-06-21/
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