For example, if you hold BTC and sell BTC futures to hedge against a price drop, the difference between the spot and perpetual or expiry prices (the basis) may widen or narrow, resulting in unexpected gains or losses. Basis = Futures price – Spot price = 51,000 – 50,000 = 1,000 Time as a factor in basis risk: Time to expiry is a key factor in basis risk. As a futures contract approaches its expiration, the futures price typically converges with the spot price, reducing the basis.