How funding works
Perpetual futures have no expiry, so exchanges need a mechanism to keep their price aligned with spot. Funding rate is that mechanism:
- When perp trades above spot, more traders are long than short → perp price pressure is upward → funding turns positive → longs pay shorts → incentive to be short grows → longs close, shorts open, perp price falls back toward spot.
- Symmetric logic for negative funding.
Each funding interval (typically 8 hours), the rate is computed from the spread between perp mark price and a spot index, plus an interest-rate component. The formula varies slightly by exchange but the mechanism is the same everywhere.
Typical funding regimes
- Bull market — sustained positive funding, often 0.01-0.05% per 8h (10-55% annualized). Longs pay continuously; this is the cost of being on the crowded side.
- Bear market — funding can turn negative, sometimes -0.1% per 8h or more during panic. Shorts pay longs — an incentive for contrarians to buy spot + short perps (basis trade).
- Crisis spikes — during deleveraging events, funding can hit extreme values (±0.3-0.5%) for a few hours before mean-reverting.
Risks and considerations
Funding is a hidden cost that eats positions slowly. A year of 0.03% per 8h positive funding compounds to ~32% annualized — meaning a long BTC perp held for a year in a typical bull market loses ~a third of notional to funding before any price move. Traders often misread “I’m up 10% on my perp long” without realizing funding has paid the short counterparty 8% over the hold.
The corollary: funding arbitrage is a durable yield strategy for patient capital. Hold spot BTC, short the perp in equal notional, collect funding. During 2021’s extreme bull, this strategy returned 30-50% annualized with near-zero directional exposure. It works best when funding is extreme (above +0.05% per 8h sustained) and breaks down when funding compresses. Always check funding before entering any perp trade — it’s the largest single determinant of perp-vs-spot performance over any meaningful hold.