Basis: the gap between spot and perp

Basis = the visible pressure between perp and spot

Basis is the gap between the perp price and the spot price at any given moment. If Bitcoin spot is trading at $60,000 and the BTC perp is trading at $60,150, the basis is $150 — or about 0.25% positive. If spot is at $60,000 and the perp is at $59,850, the basis is negative $150, or about 0.25% negative. The sign of the basis is usually the sign of upcoming funding pressure.

Most of the time, basis is small — under 0.1%, often under 0.05%. The funding mechanism keeps it that way. When basis widens, it's because leveraged traders on one side are bidding (or selling) aggressively enough to push the perp price away from spot faster than funding pressure can pull it back. Wide basis = aggressive directional flow. Narrow or flat basis = balanced positioning.

Why does basis matter for retail traders who aren't doing arbitrage? Two reasons. First, watching basis is faster than watching funding. Basis updates tick by tick. Funding only repays every 8 hours. If basis suddenly widens to +0.3% in the middle of a funding cycle, you can see the pressure building before the next funding payment confirms it. Second, basis tells you the structural state of the market. Sustained wide basis means the leveraged side is overpowering the spot side. That's information about who is driving the move.

There's also a sophisticated trade hidden in basis — the funding arbitrage — but it requires capital and execution discipline. We'll cover it in the next lesson. For now, what to take away: basis is the live signal. Funding is the lagging confirmation. They both describe the same underlying pressure, but basis tells you about it sooner.

Recap: basis = perp − spot. Sign and width tell you which side is dominant and how strongly. Updates faster than funding — useful for reading pressure in real time.