Basis in crypto perps: the perp-versus-spot premium
Updated 2026-07-04
Basis is the gap between a perpetual future's price and the spot index it tracks, expressed in basis points. When the perp trades above spot the basis is positive; when it trades below, negative. It is the raw pressure gauge that funding then tries to squeeze back toward zero.
How basis is measured
Basis compares two prices for the same asset: the perpetual's mark price and the spot index price. The formula is simple — basis_bps = (mark − index) / index × 10,000. Dividing by the index and multiplying by 10,000 puts the answer in basis points, where 1 bp is one hundredth of a percent, so a perp trading 0.5% above spot reads as +50 bps.
A positive basis means the perpetual trades above spot. That is the normal state in a market where leveraged longs are the crowded side: they bid the perp up relative to the underlying. A negative basis means the perp trades below spot, which happens when shorts dominate or during a fast sell-off where perps lead price down.
Because it is a ratio, basis is comparable across assets and across price levels. +30 bps means the same degree of premium on a $100,000 BTC perp as on a $0.15 DOGE perp, which is why it is quoted in bps rather than dollars.
Basis and the funding rate
Basis and funding are two sides of one mechanism. Basis is the observed gap right now; funding is the periodic payment that pulls that gap back toward zero. When the perp runs to a premium, positive funding charges longs and pays shorts, which discourages new longs and encourages arbitrage that presses the perp back toward the index.
So a persistent positive basis usually comes with positive funding, and a persistent negative basis with negative funding. Watching them together separates a healthy premium from a stressed one: a small positive basis with modest funding is ordinary carry, while a large basis that funding cannot pull in signals one-sided positioning that often precedes a violent snap back.
The cash-and-carry trade
Basis is the yield behind the cash-and-carry trade. A trader who holds spot and shorts the perpetual against it is delta-neutral — indifferent to the price of the asset — but collects the funding paid by longs while the basis is positive. The position earns the carry and closes when the basis compresses.
This arbitrage is exactly what keeps basis bounded. When the premium grows wide enough to be worth the capital and fees, carry desks step in, shorting the rich perp and buying spot, which mechanically pushes the perp back toward the index. Basis is therefore both a sentiment reading and the incentive that self-corrects it.
How MarketTrace computes basis
MarketTrace derives basis from Binance's premiumIndex feed, where the reference index is a multi-exchange spot composite rather than a single venue's last trade. Using a composite index avoids treating one exchange's wick as the whole market's spot price, so the basis reflects the perp against a broad view of fair value.
The result is published as basis_bps on every asset in the agent feed, alongside funding and open interest. Reading the three together — basis for the current gap, funding for the pull, open interest for how much leverage is committed — gives a fuller picture than any one number alone.
Related
Frequently asked questions
What does a positive basis mean?
A positive basis means the perpetual is trading above the spot index — the perp price is richer than the underlying. It typically reflects crowded leveraged longs bidding the perp up, and it usually comes with positive funding, where longs pay shorts at each settlement. A large, persistent positive basis is a sign of one-sided long positioning.
How is basis different from the funding rate?
Basis is the gap between perp and spot right now, measured in basis points. Funding is the periodic payment that exists to pull that gap back toward zero. Basis is the symptom; funding is the corrective force. They move together — a positive basis normally pairs with positive funding — but basis is an instantaneous price spread while funding is a scheduled cash flow between longs and shorts.
What is basis measured in?
Basis is quoted in basis points (bps), where 1 bp is one hundredth of one percent. The formula is (mark − index) / index × 10,000. Quoting it as a ratio in bps makes it comparable across assets and price levels: +25 bps is the same proportional premium on a $100,000 BTC perp as on a sub-dollar altcoin perp.
What is the cash-and-carry trade?
Cash-and-carry means holding spot and shorting the perpetual against it, leaving the position delta-neutral. While the basis is positive and funding is being paid to shorts, the trade collects that funding as yield with no directional exposure. This arbitrage is what keeps basis bounded — when the premium is wide enough, carry flows short the perp and buy spot, compressing the gap.