Kalshi Surpasses Polymarket as Bitcoin Perpetuals Draw Institutional Flow

Published by James Harris on June 8, 2026June 8, 2026

Kalshi’s open interest hit $810 million last week, a 28% jump from the prior week and a new all-time high for the platform. Two things collided to produce that number: a new product and a market that suddenly needed it.

The product is BTCPERP, the first CFTC-regulated Bitcoin perpetual futures contract, which went live on June 3. Perpetuals don’t expire, so every position opened stays on the books until the trader closes it, compounding OI in a way Kalshi’s legacy event contracts structurally cannot. Those binary yes/no contracts clear the moment they settle, which is fine for election bets but terrible for building a standing book of leveraged exposure. The timing layered a macro trigger on top of the product launch: Bitcoin dropped over 13% in a week, from roughly $74,000 to a low near $59,000, and traders who got burned by liquidations on unregulated perpetual venues rotated toward something with capped downside. Kalshi caught both flows simultaneously.

The OI comparison with Polymarket is the sharpest indicator of what has actually shifted. Kalshi’s $810 million is now 1.9 times Polymarket’s $419 million, a gap that was roughly zero at the start of the year.

That divergence reflects a strategic fork that has been widening for about 18 months. Polymarket remains a resolution market, built around discrete outcomes and settlement. Kalshi has been deliberately repositioning itself as a regulated derivatives venue, absorbing the legal and compliance overhead that comes with CFTC oversight rather than fighting it. The BTCPERP listing is the clearest expression of that bet, and the OI response suggests institutional or at least sophisticated retail capital is treating the regulatory wrapper as a feature rather than friction. For comparison, the unregulated perpetuals market on venues like Binance and Bybit runs in the hundreds of billions of notional daily, so $810 million in standing OI is still a rounding error in absolute terms, but the directional signal is clear.

The honest question the OI number leaves open is how much of it was the product and how much was the volatility. A sharp sell-off reliably drives hedging demand toward venues with defined-risk structures, and that effect fades when markets stabilize. If OI holds above $700 million through a quieter stretch in late June, the BTCPERP thesis is real. If it bleeds back toward Polymarket’s range, the sell-off did most of the work.