Kalshi Weekly Open Interest Hits Record $810 Million

Data from Artemis shows that Kalshi’s weekly Open Interest (OI) reached a new high this past week with $810 million. That’s around a 28% increase from the previous week and beating the highs that were set in mid may. The number carries more weight rather than a raw volume print would. Volumes can spike and disappear within a day. OI, on the other hand, highlights money that’s parked and stays. In Kalshi, this metric has been growing rapidly.

The Launch of BTCPERP Rewired the Math

Kalshi listed BTCPERP, the first CFTC-regulated Bitcoin perpetual futures contract, went live on June 3 and this has had a great impact on growing OI on the platform. Since perpetuals don’t expire, a position can be held indefinitely and therefore keeps feeding OI for as long as the trader keeps that position open. Kalshi’s main product until this has been event contracts that expire on a said date and clear off the books the moment they settle. Those were never built to accumulate OI the way a perpetual can and hence we see the strongest OI week yet for the platform.

A Sell-Off Sent Traders Hunting for Capped Downside

Timing did the rest. Last week, Bitcoin experienced its sharpest weekly drop this year of over 13% from the highs of around $74K to a low of $59K before closing at around $63K. Kalshi’s event contracts cap losses at the stake, nothing more. Traders tend to want that when prices are dropping and leverage is blowing up on other venues. That instinct kicked in right as BTCPERP went live, so the platform caught the rotation and the new product at once.

OI Now Sits Well Above Polymarket

The record OI above $800 million now means Kalshi is way ahead of its rival Polymarket in this department. Last week, Polymarket saw $419.9 million in OI, meaning Kalshi’s OI is now 1.9x Polymarket’s. The gap is glaring given the fact that this number was basically split equal at the start of the year. Both the platforms started as event-based prediction markets trading the same sort of yes/no outcome. Polymarket still leans toward the binary, resolve and settle model. Kalshi has spent the past year or so getting closer to a regulated derivatives exchange. The OI increase is the closest indication yet that the shift is attracting capital at scale.

What the Number Actually Signals

Open interest reads differently from a one-day volume record. It points to positions traders mean to hold, contracts that keep throwing off fees and data, and a user base treating Kalshi as a place to keep exposure rather than settle a quick wager. For a company that spent its early years fighting the CFTC for the right to operate at all, $810 million in standing OI marks how far that regulatory bet has carried it. The open question is whether the number holds once the early-June volatility cools, or whether the sell-off, not the product, did most of the lifting.