Funding Rates on Perps: The Cost Nobody Prices In

The perpetual funding rate is the price of not having an expiry date. Perpetual futures never settle, so nothing mechanically forces the contract to trade at spot; funding is the mechanism that drags it back. It is a periodic transfer between longs and shorts, paid from one side of the book to the other, and it is not a fee the venue keeps.

Most traders file the perpetual funding rate next to commissions and slippage as a rounding error. That framing only survives short holding periods. Funding repeats every few hours, applies to the full notional rather than to the margin you posted, and accrues whether or not the position ever moves in your favour.

• Funding is a transfer, not venue revenue. When the rate is positive, longs pay shorts; when negative, shorts pay longs. The venue is an intermediary, not a beneficiary.
• It applies to notional, not margin. A 5x position pays funding on five times the capital committed, which turns a small rate into a large drag on equity.
• Annualising is the only fair comparison. A rate per interval means little until it is multiplied into a yearly figure and set against borrow cost or yield.
• It is regime-dependent. Rates trend, flip and get capped, so a cost measured in a calm week is not the cost you will pay in a trending one.

What the perpetual funding rate actually is

It is a payment calculated periodically on position notional, using a rate derived from the gap between the contract price and an index of spot prices. Most venues sample that gap, add or subtract a fixed interest component, then clamp the result inside a cap. The clamp matters: it means funding can stop fully correcting the gap when positioning is extreme.

Intervals are venue-specific. Eight hours is common, but one-hour and four-hour schedules exist, and a venue may change them. A rate of 0.01% means nothing until you know how often it is charged — the same number on a one-hour schedule is eight times the annual cost.

The transfer, not the invoice

Funding moves between traders. If you are flat at the timestamp, you pay nothing for that interval, which is why closing a position a minute before settlement avoids the charge entirely. If you are hedged — long the perpetual and short spot, or long one venue and short another — you may be receiving on one leg and paying on the other, and the net is what belongs in your cost model.

Why the rate moves

The rate follows demand imbalance. When leveraged longs crowd the book, the contract trades above spot, the premium turns positive and longs pay. When the book leans short, the sign flips and shorts pay longs. Because the index and the cap differ by venue, two platforms can quote materially different rates for the same asset on the same day. That spread is a real arbitrage, and it is also a warning: the rate you see is a local price for leverage, not a property of the asset.

Annualising the perpetual funding rate

Annualising converts a per-interval charge into a number you can compare with everything else you hold. The simple version multiplies the rate by the number of intervals in a year:

Annual cost = rate per interval × intervals per day × 365

Take 0.01% per eight hours. That is three charges a day, so 0.03% a day, so roughly 10.95% a year on notional. At 0.05% per eight hours the same arithmetic gives 0.15% a day and 54.75% a year. At 0.1% per eight hours it gives 0.30% a day and 109.5% a year.

The compounding version is slightly higher, because each payment is taken from a shrinking balance rather than paid once at the end. For 0.01% per interval over 1,095 intervals, (1.0001)^1095 − 1 is about 11.6%, against 10.95% simple. The gap widens with the rate: 0.05% per interval compounds to roughly 72.9% rather than 54.75%, and 0.1% compounds to roughly 199%.

Now attach it to leverage. A trader holding $10,000 of notional with $2,000 of margin at 0.05% per eight hours pays about $5 a day, or $1,825 a year — against $2,000 of equity. The position does not need to lose on price to lose most of its capital. That is the number nobody prices in.

A position that is flat on price is not flat on cost. Funding keeps charging the notional long after the trade has stopped being interesting.

Funding versus other holding costs

Funding belongs in the same ledger as every other cost of carrying exposure, because that is the only way to see which one dominates at your holding period.

Read down the last column. Fees are a fixed toll on entering and exiting; funding is rent on staying. A strategy with a two-day horizon can ignore funding and be roughly correct. A strategy held for a quarter cannot, and one held for a year is effectively a funding trade whether the author admits it or not.

Where the estimate breaks

Three things routinely invalidate a neatly annualised figure: the schedule changing, the rate being capped, and the sign flipping mid-hold. A model that assumes a constant positive rate will overstate the cost of a long in a falling market and understate it in a rising one.

Caps, clamps and pinned rates

When the calculated rate exceeds the venue cap, the effective rate is the cap. In a violent move the contract can trade far from spot while funding sits pinned at its ceiling, unable to close the gap. Traders who assume funding will always arbitrage the basis away are assuming a mechanism that is deliberately bounded.

Sign changes and hedged legs

Funding flips. A long that paid for six weeks can turn into a receiver within a day, which means the annualised figure is an average of regimes, not a constant. For hedged books, the correct measure is the net of both legs across both venues, including the intervals where the two schedules do not align. Partial overlap is where the accounting quietly goes wrong.