one way to think about a financial derivative is as an agreement about a future price. you and i disagree about where bitcoin will be in three months. rather than wait and see, we formalize our disagreement into a contract: if bitcoin is above X at date Y, you pay me; if it's below, i pay you. the contract settles on date Y, we move on, one of us is richer. this is a futures contract. it's been around since the 1800s, when farmers wanted to lock in crop prices, and it works fine. the small inconvenience is that if you want to stay exposed to bitcoin after the contract expires, you have to "roll" into the next one, paying bid-ask spreads each time and dealing with the fact that the new contract might trade at a different price than you'd like. not a huge deal. just friction.
perpetual futures eliminated that friction, and in doing so accidentally became the dominant instrument in crypto markets. the innovation is conceptually simple: what if the futures contract never expired? you just hold a position indefinitely, paying or receiving a "funding rate" that keeps the perpetual price tethered to the spot market. bitmex pioneered this around 2016. by 2022, perpetuals accounted for something like 70-80% of all crypto derivatives volume. it's a genuinely interesting example of a mechanism design choice reshaping an entire market.
the funding rate is the clever part. here's the problem it solves: if a perpetual contract has no settlement date, what keeps it from drifting arbitrarily far from the actual bitcoin price? the answer is: a continuous transfer of money between the longs and the shorts, calibrated to push prices back toward spot. if the perpetual is trading above spot — meaning market sentiment is bullish, more people want to be long than short — longs pay shorts a small periodic fee. this creates an incentive for new shorts to enter (they're getting paid!) and for marginal longs to exit (they're paying!). the price gets pushed back down. if perps are below spot, the flows reverse. the mechanism self-corrects.
funding rates are usually small. something like 0.01% per 8 hours is typical in calm markets. that's about 11% annually if it stayed constant, which it doesn't — it fluctuates with sentiment. but when markets get crowded, funding rates spike. during the bitcoin bull run of late 2020, funding rates hit 0.1-0.3% per 8 hours. annualized, that's 450-1350%. longs were paying shorts enormous amounts to maintain their positions. this is the funding rate functioning as a sentiment indicator — when it gets that extreme, the market is telling you that positioning is stretched. experienced traders use this as a signal to fade the move.
the weird thing perpetuals did to crypto is flip the relationship between spot and derivatives. in traditional markets, the spot market is the "real" market — equities trade on exchanges, the futures markets are secondary. in crypto, perpetuals became larger than spot. the derivatives tail began wagging the spot dog. this makes a certain kind of sense: perpetuals offer leverage (typically 10-100x depending on the exchange and collateral), which attracts larger sophisticated participants, which concentrates price discovery activity. a well-capitalized trader who thinks bitcoin should be $10,000 higher can take a 10x leveraged position on that belief in perpetuals. the same trader taking an unlevered spot position has much less at stake per dollar deployed. leverage concentrates conviction into price impact, which is one definition of price discovery.
the other thing perpetuals did is separate price exposure from asset custody. to trade spot bitcoin, you need to own bitcoin — which means custody, key management, withdrawal limits, and the other annoyances of actually holding a cryptocurrency. perpetuals give you the economics of owning bitcoin (or being short bitcoin) without actually owning anything. you post dollar-denominated collateral and take a levered position. this made crypto markets accessible to professional traders who understood financial derivatives but had no interest in learning to manage a hardware wallet, and it brought in a class of participant — the institutional derivatives trader — who significantly increased market efficiency.
bitmex, which invented this, eventually got caught in regulatory trouble (its founders were charged with violating US bank secrecy laws), but by then the genie was out of the bottle. binance, ftx, bybit, and dydx all built perpetuals as core products. the mechanism spread independently of the institution that created it. ftx is famously gone now, which is worth noting — sam bankman-fried built one of the world's largest perpetuals exchanges and then allegedly used customer funds to cover trading losses at his affiliated hedge fund, which is a much more prosaic failure mode than "clever mechanism design." the mechanism was fine. the custodian committed fraud. these are different problems.
anyway. the funding rate is a rule that creates information flow that wouldn't exist otherwise. it's not a complex rule. it's basically: if longs outnumber shorts, longs pay shorts; if shorts outnumber longs, shorts pay longs. from that rule you get a sentiment indicator, a self-correcting price mechanism, and the dominant trading instrument in a multi-trillion dollar asset class. one clever mechanism, deployed at scale, can reorganize who participates in a market and how prices are discovered. that's what happened here.