The distinction that matters
Volume counts trades. Open interest counts positions still standing. The same 1,000 shares changing hands ten times produces 10,000 in volume and no change at all in open interest.
So volume measures activity and open interest measures commitment. A market with heavy volume and flat open interest is being traded around, not accumulated: money is moving through without taking a side.
How to use open interest
Rising open interest with a rising price means new money is arriving on the Yes side, which says more than price alone. Rising price on falling open interest usually means existing shorts are closing, and that move tends not to hold.
Open interest also sets the ceiling on how much can be traded out. A market where one participant holds most of the outstanding contracts is a market where exiting a position will cost more than the current spread suggests.
Open interest on 0xinsider
0xinsider does not show open interest. Market pages show volume traded, and the live feed lists the large trades inside that volume, so a build-up in a quiet market shows as repeated large buys on one side before the price moves.
