What Is a Perpetual Future?
The dominant product in crypto trading isn't spot — it's the perp. Understand what it is, how it stays glued to spot without ever expiring, and why this single innovation reshaped the entire market.
Walk into any crypto exchange and look at the volumes. Spot BTC turnover on a typical day: a few billion. Perpetual futures on the same day: tens of billions. The perp is where the market actually trades. If you don't know how it works, you're reading the smaller chart.
01Where perpetuals came from
To understand the perp, you need to know what a regular future is first.
You sign a contract today: in nine months, you'll pay the venue $8,000 and they'll host your event. The price is locked, the date is locked. Nine months later, the contract expires — money changes hands, the venue is yours for the day, the contract is done. That's a traditional futures contract: agreement now, settlement at a specific date in the future.
Traditional futures (still traded on CME for BTC) work exactly this way: March futures, June futures, each with an expiry date. When that date arrives, the contract settles. If you want continued exposure, you "roll" — close the expiring contract, open the next one. It's manageable but tedious, especially for crypto traders who want to hold positions for weeks or months without thinking about expiries.
In 2016, BitMEX launched something new: a future that never expires. They called it a "perpetual swap" or "perpetual future" — perp for short. No expiry date. You open a position, you close it whenever you want. It became, by a wide margin, the most popular crypto product ever created.
02The obvious problem this creates
If a futures contract never expires, how does its price stay tied to the actual price of Bitcoin?
Traditional futures are anchored by their expiry — at the settlement date, the contract must equal spot, because that's how it settles. Between now and expiry, arbitrageurs keep the price close to spot because they know it'll converge. Take away the expiry and that anchor is gone. A perp could theoretically drift forever above or below spot, untethered.
The fix is a mechanism unique to perps. It's called the funding rate, and it's a small payment that flows between longs and shorts every few hours, designed to push the perp price back toward spot whenever it drifts.
A traditional future uses expiry to anchor itself to spot. A perpetual future uses funding instead. Same job, different mechanism. That's the entire conceptual leap.
03What you actually trade
When you open a long position on a BTC perpetual at $63,000, you're not buying Bitcoin. You're entering a contract whose value tracks the price of Bitcoin. If BTC rises to $65,000 you can close at a $2,000 gain (per BTC). If it falls to $61,000 you take a $2,000 loss. You never touched an actual coin.
Key properties of crypto perps:
- Cash-settled. Profit and loss flow in stablecoins (USDT/USDC) or in BTC, depending on the contract. No physical delivery of Bitcoin ever happens.
- Leveraged. You post a fraction of the position size as margin. 10× leverage means $1,000 margin controls a $10,000 position — your gains and losses are amplified 10×.
- Bidirectional. You can go long or short with equal ease. Selling a perp doesn't require borrowing anything first.
- 24/7. No market close. Funding pays around the clock.
04Why this matters for everything else
Almost every concept you'll learn in the rest of this section flows from perps:
- Funding rate exists because perps don't expire — it's the anchor.
- Mark price exists because the last traded price on a leveraged product can spike unfairly, so exchanges use a smoothed price for liquidations.
- Liquidations exist because leverage means small adverse moves can wipe out your margin.
- Basis trading exists because perps can drift from spot — and that gap is a tradeable edge.
- Open interest on perps tells you how much leveraged positioning is alive in the system.
A perpetual is a futures contract without an expiry date, kept aligned with spot by a small funding payment between longs and shorts. Everything else — liquidations, leverage, the way price actually behaves in crypto — is downstream of this design choice.