Basis

In crypto perpetual futures, the basis — the difference between the perpetual contract price and the spot index — is the market's real-time thermometer for speculative demand versus hedging supply. Unlike traditional futures where basis reflects cost-of-carry and time-to-expiry, the perpetual basis is a pure measure of the supply-demand imbalance for leveraged exposure.

What the basis encodes

The basis in perpetual futures maps directly onto the demand for leverage. Garriott & Ruf (2020) showed that the futures-spot basis in equity index markets captures the marginal cost of leverage — and in crypto, where leverage is the primary purpose of the perpetual contract, this relationship is even more direct.

Positive basis (contango): Longs are willing to pay a premium for leveraged exposure through the perpetual. Speculative long demand exceeds the arbitrage capacity of basis traders who would short the perp and buy spot. This is the signature of bullish crowding.

Negative basis (backwardation): Short demand exceeds long demand. Hedgers or bearish speculators dominate the perpetual flow, pushing the price below the spot index. In crypto, persistent backwardation often signals genuine fear — participants paying a premium to short.

What we track

• Mark-index basis (bps) — the core spread between the exchange's mark price and the underlying spot index
• Mark-to-trade spread — the difference between the official mark price and the last actual trade. Exchange mark prices are smoothed (EMA-based) to resist manipulation of liquidation triggers. When the last trade diverges from the mark, either price is moving faster than the smoothing can track, or there's a data quality anomaly — both worth flagging.
• Basis mean and standard deviation — the full distribution of basis within the interval, not just the endpoint

Basis standard deviation captures instability in the perp-spot relationship. When it's elevated, the arbitrage mechanism is under stress — either from active unwinding of basis trades or from directional pressure that overwhelms the basis-trading capacity. This maps to the "limits of arbitrage" framework of Shleifer & Vishny (1997): when capital constraints prevent arbitrageurs from closing the gap, the basis can persist at economically significant levels.

The overheating signal

Persistent high basis + extreme positive funding + rising open interest is the classic "perpetual overheating" setup. The market is simultaneously leveraged long, paying for that leverage, and adding more. This configuration tends to resolve violently — when the first wave of liquidations starts, the deleveraging cascade compresses the basis and funding in hours. This is the crypto-specific expression of the Brunnermeier & Pedersen (2009) liquidity spiral: market losses trigger margin calls, which trigger forced selling, which triggers more losses.

References:

• Garriott, C. & Ruf, K. (2020). "The Futures Basis and the Cost of Leverage." Bank of Canada Staff Working Paper.
• Shleifer, A. & Vishny, R.W. (1997). "The Limits of Arbitrage." Journal of Finance, 52(1), 35–55.
• Brunnermeier, M.K. & Pedersen, L.H. (2009). "Market Liquidity and Funding Liquidity." Review of Financial Studies, 22(6), 2201–2238.