Why Do Perpetual Futures Have Funding Rates?.

Perpetual futures have funding rates because they never expire. A traditional futures contract is pulled back to the spot price by its settlement date, since at expiry the contract and the asset must be worth the same thing. A perp has no expiry, so the exchange replaces that gravitational pull with a recurring cash payment between traders: when the perp trades above the underlying index, longs pay shorts, which makes being long expensive and being short paid, and the pressure pushes the perp back down toward spot. When the perp trades below the index, the payment flows the other way.

That is the entire purpose of the mechanism. It is not a fee the exchange collects, and on most venues the exchange takes no cut of it at all. It is a peer-to-peer incentive designed to keep a contract with no expiry date glued to the price of the thing it tracks.

The cleanest way to internalize it is to ask what would happen without it. A perp with no funding and no expiry is just a number people trade against each other, with nothing anchoring it to the asset’s real price. If enough traders wanted leveraged long exposure, the perp could float 5 percent above spot indefinitely, because no settlement ever comes to punish the gap. Funding makes that gap expensive to hold. Whoever is on the crowded side of the trade pays whoever is on the uncrowded side, continuously, until the crowding eases or the price converges.

This is also why funding doubles as a positioning signal, which is most of what I use it for. The rate is a live measurement of which side of the book is crowded and how badly. Persistent positive funding means longs are paying for the privilege of being long, which tells you where the leverage has piled up. Extreme negative funding tells you shorts are paying heavily to stay short, which is often more interesting, and is the condition my screener is built around.

The mechanics of how the number is computed vary by venue, but the skeleton is shared almost everywhere: a premium index measuring how far the perp sits from spot, plus a small fixed interest component, with a clamp to keep the adjustment orderly. Hyperliquid’s documentation and Variational’s documentation both publish this same structural formula. I walk through the moving parts in how the rate is built, who actually pays whom in who pays funding, and how often the payment lands in how often funding is paid.

One nuance worth carrying with you: funding keeps the perp near spot on average, not at every moment. The payment arrives on a schedule, and between payments the perp can and does drift. That gap between the snapshot the mechanism enforces and the live price you trade is where most of the interesting behavior in this market lives, and most of what this publication covers.