Open interest is the amount of a contract that is open at a given moment. On 4 October 2026, a Sunday, the S&P 500 perp held about $349 million of it. The Nasdaq 100 perp held about $247 million. Those are levels. The more useful question on a weekend is how they are changing as Monday gets closer.
Not the open interest that builds walls
An options trader hears open interest and thinks of strikes. Option open interest sits at specific strikes, and that is what builds the walls on a dealer map. Perp open interest has no strikes. It is one number for the whole contract. It builds no walls and has no gamma. It measures how much exposure is open on that venue and nothing about dealer hedging in SPY.
Rising into Monday
If open interest climbs across the weekend, new positions are being opened. Read it with price. Rising open interest while the perp rises says the new positions are arriving into strength. Rising open interest while the perp falls says they are arriving into weakness. Either way the move has fresh money behind it.
Falling into Monday
If open interest drops as Sunday evening nears, positions are being closed. Some holders use the perp to carry exposure through hours when nothing else trades, and stand down when futures reopen. A move that comes with falling open interest is existing positions leaving, which is weaker evidence than new ones arriving. The price and open interest quadrant lays out all four combinations.
A caution on dollar figures
Open interest quoted in dollars moves with price. If the perp rises one percent and nobody trades, the dollar figure rises too. A small change in dollar open interest beside a similar change in price may be nothing more than that.
Why this needs a record
The venue serves price history and funding history. It does not serve open-interest history. You can ask what open interest is now and not what it was on Friday. A change needs two readings, so somebody has to have written the first one down. NoVo’s collector has recorded every perp’s open interest on every pass since 4 October 2026. The open interest history the venue does not serve explains why that date is where the record begins.
The record is young. Where it does not yet reach back a full day or a full week, the dashboards label the change with the span it really covers.
Where to read it
The Stocks On-Chain tab on the NoVo Crypto Market Map shows each perp’s open interest, its change and a chart of the recorded history. On Trader the index perps sit on the Perps & Futures tab beside the SPY, QQQ and IWM maps. A rising figure is a description of positioning on one venue. It is never a forecast of Monday.