Introduction
Perpetual futures and expiry futures represent two distinct derivative structures that serve different trading purposes. Perpetual futures lack expiration dates and use funding rates to maintain price alignment with spot markets. Expiry futures carry fixed settlement dates and converge to spot prices only upon maturity. Understanding these mechanisms helps traders select appropriate instruments for speculation, hedging, and arbitrage strategies.
Key Takeaways
- Perpetual futures have no expiration date; expiry futures settle on predetermined dates
- Funding rates keep perpetual futures prices tethered to spot markets every 8 hours
- Expiry futures require position rollover or settlement at maturity
- Both instruments offer leverage but carry distinct risk profiles
- Trading costs differ: perpetual futures incur recurring funding payments; expiry futures cost accrues only to settlement
What Is a Perpetual Future
A perpetual future is a derivative contract that never expires, allowing traders to hold positions indefinitely. The exchange does not set a delivery date or settlement month. Instead, a funding mechanism keeps the contract price close to the underlying asset’s spot price. According to the Bank for International Settlements (BIS), perpetual futures have become a dominant trading vehicle in crypto markets since their introduction by BitMEX in 2016.
Traders deposit initial margin and receive or pay funding every 8 hours based on market conditions. The funding rate adjusts continuously, creating an arbitrage loop that maintains price consistency. This design eliminates the need for contract rolling, a requirement that characterizes traditional futures positions.
Why Perpetual Futures Matter
Perpetual futures provide liquidity depth and 24/7 trading availability that spot markets cannot match. Institutional traders use these instruments to hedge exposure without worrying about contract expiration timelines. Retail traders access high leverage without managing complex rollover schedules.
The funding rate mechanism reflects market sentiment in real time. Positive funding indicates demand for long positions; negative funding signals short pressure. This price discovery function makes perpetual futures valuable for understanding broader market dynamics, as documented in academic research on crypto derivatives markets.
How Perpetual Futures Work
The funding rate calculation follows this structure:
Funding Rate = Interest Rate + (Premium Index – Interest Rate)
The interest rate component typically stays fixed at 0.01% per period. The premium index measures the deviation between perpetual futures price and mark price. When the contract trades above spot, the premium index turns positive, pushing the funding rate higher. When the contract trades below spot, the premium index turns negative, reducing or inverting the funding rate.
Every 8 hours, traders with winning positions pay those with losing positions. If funding rate equals 0.01%, long traders pay short traders 0.01% of their position value. If funding rate equals -0.02%, short
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