A trader who wants continuous bitcoin price exposure can buy bitcoin or open a contract that never reaches a scheduled expiry. That second instrument is a perpetual future, commonly called a perpetual or perp. Its long side generally gains as the marked value rises, but the position remains a contractual venue balance rather than ownership of bitcoin.
Removing expiry solves one inconvenience but creates another. A dated future naturally approaches its settlement reference as expiry nears, whereas a perpetual could drift away indefinitely. Crypto venues therefore combine a price index, a mark-price method, recurring funding transfers, and margin rules to connect the contract to spot markets and manage leveraged accounts.
What you will learn
- Explain why perpetual futures need an anchoring mechanism
- Trace how index price, mark price, funding, and margin interact
- Evaluate liquidation and venue risk without assuming uniform contract rules
The contract has no maturity date
A dated future specifies when and how final settlement occurs. A perpetual remains open until the participant offsets or closes it, the venue liquidates it, or another contract rule ends it. This makes continuous exposure convenient, but duration is economically meaningful because funding payments, collateral requirements, fees, and venue risk can accumulate for as long as the position remains open.
Every perpetual has specifications: contract unit, quote currency, collateral asset, settlement asset, index composition, funding schedule, margin tiers, and position limits. A coin-margined contract can change collateral value at the same time as the position moves, while a stablecoin-margined contract introduces the stability and issuer risks of that collateral. The ticker alone does not reveal these differences.
Index and mark prices serve different jobs
The index price is usually built from spot prices across selected venues. Its purpose is to represent the broader underlying market rather than one isolated derivative trade. The mark price is a calculated fair-value reference used for unrealized profit, loss, and often liquidation decisions. A last trade can jump briefly, so using it alone could allow a small anomalous transaction to trigger unfair liquidations.
Methodology remains a source of risk. Index constituents can become unavailable, trade at stale prices, or experience withdrawal and banking problems. Published constituent, outlier, and missing-data rules can reduce manipulation exposure, but no index guarantees perfect representation during fragmented or disorderly markets.
Funding encourages alignment with spot
Funding is a periodic payment exchanged between long and short position holders under a venue's formula. When a perpetual trades persistently above its spot reference, longs commonly pay shorts; when it trades below, shorts commonly pay longs. The payment changes the relative cost of holding each side and can attract positions that push the contract back toward spot.
Funding is not an interest payment from the underlying blockchain and is not usually a fee retained by the exchange, though venue implementations vary. It can change sign and magnitude. A favorable rate can disappear before the next interval, and a strategy attempting to collect funding can lose through basis movement, execution costs, liquidation, or failure of one side of a hedge.
Liquidation protects the venue, imperfectly
A venue liquidates positions when remaining account equity approaches the amount needed to cover further losses. A liquidation engine may close positions into the market, draw on an insurance fund for deficits, or automatically reduce profitable opposing positions in extreme conditions. These controls seek to prevent one account's loss from becoming another customer's unpaid gain.
Fast price moves and thin liquidity can defeat orderly assumptions. Closing many similar positions may move the book, produce worse fills, and deepen losses. Insurance funds can be insufficient, and automatic deleveraging can alter positions that appeared profitable. Contract users therefore depend on both market liquidity and the venue's operational, legal, and financial design.
Common misconceptions
“A perpetual futures contract is the same as an ETF that holds cryptoassets.”
A perpetual is a margined bilateral market exposure with funding and liquidation mechanics. An ETF share represents an interest in a regulated fund under a different custody and legal structure.
“No expiry means a perpetual position can be held forever without additional cost.”
Funding, fees, collateral changes, margin calls, venue access, and liquidation constraints continue for the life of the position and can end it involuntarily.
Risks and limitations
- Liquidation can close a leveraged position before the participant's longer-term view can be tested.
- A defective or disrupted index can distort marks, funding, and risk controls across many accounts.
- Collateral can lose value or become unavailable precisely when additional margin is required.
- Exchange insolvency, rule changes, outages, and automatic deleveraging add risks absent from direct asset ownership.
Key takeaways
- A perpetual is a derivative contract without scheduled expiry, not the underlying asset.
- Index prices represent a spot reference; mark prices commonly drive account risk calculations.
- Funding changes the cost of long and short exposure to encourage convergence with spot.
- Margin and liquidation rules vary by venue and must be read at the contract level.
- Market liquidity and venue safeguards jointly determine behavior during stress.
Primary and further reading
Test your understanding
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