What is Open interest?

Open interest is the total size of derivative contracts that have been opened and not yet closed. Every contract has a long and a short, so open interest counts each one once: if one trader opens a one-BTC long against another trader’s new one-BTC short, open interest rises by one BTC. Venues publish it per market, in coins or in dollars.

It moves differently from volume. Volume counts every trade, including a position passing from one trader to another; open interest changes only when the total amount at stake changes. A new long against a new short adds to it, a closing long against a closing short subtracts from it, and a trade where one side opens while the other closes leaves it where it was. A market can trade heavily all day and end with the same open interest it started with.

Traders read it next to price and funding. Price rising with open interest rising suggests new positions are driving the move; price rising while open interest falls suggests shorts closing. High open interest together with an extreme funding rate means a crowded market, and crowded markets are where cascades of liquidations start. None of it predicts direction on its own: open interest describes how much is riding on a market, not which way it goes.

Open interest describes the market; a portfolio describes your piece of it. TrueHold does not chart open interest. It reads your own open positions on Hyperliquid by address, on Lighter through a read-only token and on connected exchanges by read-only key, and totals their size and PnL with the rest of what you hold.