Guide

Perpetual futures explained

A perpetual future (or perp) is a derivative contract that lets you bet on an asset's price going up or down — with leverage — and never expires. Unlike quarterly CME Bitcoin futures or equity index futures with fixed settlement dates, perps stay open indefinitely until you close the position or get liquidated. Crypto popularized the format: Binance, Bybit, dYdX, Drift, and Hyperliquid all run high-leverage perp markets on Bitcoin, Ethereum, and hundreds of altcoins. The mechanism that keeps perp prices anchored to spot is the funding rate — periodic payments between longs and shorts. That sounds technical, but understanding funding, mark price, and liquidation math is the difference between using perps as a hedging tool and bleeding collateral in a one-directional market. This guide explains how perpetual swaps work, how they differ from margin spot and options, and what retail traders should verify before opening a position.

Perps vs dated futures vs spot

Three ways to express a bullish view on Bitcoin illustrate the differences:

Spot: Buy BTC with cash. You own the asset. No funding, no liquidation from leverage (only price risk). Capital tied up 1:1.
Dated future: Agree to buy BTC at a fixed price on a set expiry (e.g. CME quarterly). Converges to spot at settlement. Basis reflects carry cost and time to expiry.
Perpetual future: Synthetic exposure with no expiry. Price tracks spot via funding payments. You post collateral (usually stablecoins or USD) and choose leverage — 2x, 10x, 50x depending on venue rules.

Perps are cash-settled: you never take delivery of the underlying. P&L is mark-to-market against your collateral. That makes them efficient for short-term directional bets and hedges, but the leverage dial is what kills undercapitalized accounts during volatility spikes.

How funding rates keep perps near spot

If a BTC perp trades above spot, longs are paying a premium to stay long — the market is bullish and overcrowded on one side. Exchanges solve this with a funding rate: every few hours (typically 8 hours on CEXs, sometimes hourly on DEXs), one side pays the other a fee proportional to position size and the rate.

Positive funding: Longs pay shorts. Perp price is above index. Incentivizes shorts to enter and longs to close — pressure pushes perp down toward spot.
Negative funding: Shorts pay longs. Perp trades below index. Rewards longs for absorbing the discount.

Funding is not a fee to the exchange (though venues may take a cut). It is a peer-to-peer transfer that anchors the perpetual price to an external index price — usually a volume-weighted average from major spot venues. In raging bull markets, longs can pay 0.1% or more every 8 hours. On a 10x position held for weeks, funding alone can exceed a spot trader's entire move. Always annualize the current funding rate before sizing a long-held perp.

Mark price, index price, and last traded price

Exchanges display three prices. Confusing them causes surprise liquidations.

Last traded price: What the most recent buyer and seller agreed on. Can spike on thin liquidity or a fat-finger order.
Index price: Composite spot reference from external exchanges. Used to calculate funding.
Mark price: Fair value used for unrealized P&L and liquidation triggers. Usually index price plus a basis adjustment or a moving average of the perp itself to filter manipulation.

Liquidation engines watch mark price, not last traded. During a flash crash on the perp order book, your position may liquidate even if spot barely moved — or vice versa, you may survive a wick that never hit the index. On-chain perps add oracle risk: if the price feed lags or is manipulated, liquidations can be unfair. Check how your venue defines mark price in the docs before trading size.

Long, short, leverage, and liquidation

Opening a long perp profits when price rises; a short profits when price falls. You post initial margin as collateral. Leverage multiplies notional exposure: $1,000 collateral at 10x controls $10,000 of BTC exposure. Gains and losses apply to the full notional, not just your margin.

When losses erode collateral below the maintenance margin threshold, the exchange's liquidation engine closes your position — often at a bad price, with an additional liquidation fee. In extreme moves, the insurance fund or socialized losses (on some venues) absorb residual deficit. Cross-margin pools all your collateral across positions; isolated margin caps loss to one position's collateral. See our margin trading guide for the full mechanics.

Liquidation cascades happen when falling prices trigger forced sells, which push price lower, triggering more liquidations. Crypto perp markets are notorious for this during leverage-heavy rallies. Open interest — total outstanding perp contracts — is a useful gauge: very high OI near all-time highs often precedes violent deleveraging.

Centralized vs decentralized perpetuals

CEX perps (Binance, Bybit, OKX) offer deep liquidity, sub-second matching, and up to 100x+ leverage on majors. You deposit into a custodial account. Counterparty risk — exchange insolvency, withdrawal freezes — is real (FTX, 2022). Regulation varies by jurisdiction; US retail often cannot access these venues directly.

DEX perps run on-chain with smart contracts and DeFi collateral. Examples include dYdX, GMX, Drift (Solana), and Hyperliquid. You keep custody in a wallet; trades settle on-chain or via off-chain order books with on-chain settlement. Trade-offs: lower liquidity on alts, oracle dependence, gas or priority fees, and smart-contract exploit risk. Advantages: permissionless access, transparent liquidation rules, and no single entity holding all deposits.

Hybrid models (off-chain matching, on-chain custody) try to split the difference. Regardless of venue type, read the insurance fund size, maximum leverage per asset, and what happens when the fund is depleted.

Perps vs options: when each tool fits

Perps and options both offer leveraged exposure, but the risk profiles differ sharply.

Perps: Symmetric linear payoff. Losses scale 1:1 with adverse moves (times leverage). No time decay, but funding is a continuous cost. Best for short-to-medium directional views where you want delta exposure without picking a strike or expiry.
Options: Asymmetric payoff. Maximum loss is the premium paid (for buyers). Time decay (theta) erodes long options. Better for defined-risk bets, hedging tail risk, or expressing views on volatility via Greeks.

A protective put caps downside on spot holdings; a short perp hedges delta without upfront premium but carries funding and liquidation risk. Many professional desks combine spot + options for structure; perps are the simpler — and more dangerous — retail shortcut.

Common mistakes and hidden costs

Ignoring funding: Holding a crowded long through weeks of positive funding can erase gains even if price is flat.
Max leverage on alts: Low-liquidity perps wick harder. 20x on a mid-cap token is not equivalent to 20x on BTC.
Cross-margin complacency: One bad position can drain collateral backing profitable ones.
Chasing negative funding: Earning funding as a short sounds free until a short squeeze rips 30% in hours.
No stop or size plan: Perps demand explicit position sizing and loss limits. "I'll close manually" fails when the app lags during a crash.
Tax and reporting: Perp P&L may be treated differently than spot in your jurisdiction. Funding payments add accounting complexity.

Retail checklist before opening a perp

Understand funding schedule, current rate, and annualized cost for your hold period.
Know whether margin is cross or isolated; set isolated for experimental positions.
Verify mark-price formula and liquidation fee on your venue's docs.
Size so a 10–15% adverse move does not hit maintenance margin at your leverage.
Check open interest and order-book depth for your asset — thin books gap on liquidations.
Keep most capital in spot or low-leverage strategies; treat perps as a small risk bucket.
Use hardware or multisig custody for collateral wallets on DEX perps when size warrants it.

Key takeaways

Perpetual futures are non-expiring, cash-settled derivatives pegged to spot via funding payments between longs and shorts.
Funding rates are a real carrying cost (or credit) — not optional background noise.
Liquidation uses mark price, which can diverge from last trade during thin or manipulated books.
Leverage is symmetric: perps amplify losses as fast as gains, with no premium cap like long options.
CEX perps offer liquidity; DEX perps offer custody — both carry distinct counterparty and smart-contract risks.
Most retail portfolios do not need perps. If you use them, low leverage and explicit risk budgets are non-negotiable.