Funding rate
A periodic payment between longs and shorts that keeps a perpetual contract tied to spot — and differs from exchange to exchange.
A perpetual contract never expires, so nothing forces it to converge to spot. Funding does that job: when the perp trades above the index, longs pay shorts; when it trades below, shorts pay longs. Most venues settle every eight hours, some every four or every hour.
The rate is set from each exchange's own premium index and its own crowd of open interest, which is why the same contract can pay +0.03% on one venue and −0.01% on another at the same moment. That divergence is the whole basis of funding arbitrage.
Funding is charged on position notional, not on margin, and it is paid only if you hold through the settlement timestamp. Entering a minute before a large payment and exiting after it is a strategy in itself — and a crowded one, which is why the rate often decays right before settlement.