By Crypto Loop · Updated 2026-10-06T20:48:28.943Z
What perpetual futures are trying to solve
A perpetual future is a derivative contract that tracks an underlying asset without a fixed expiry date. In simple terms, it lets traders express a view on price direction or hedge exposure while settling gains and losses through the contract rather than by taking delivery of the underlying asset. The structure is designed to keep the contract near the underlying market even though it does not expire like a traditional futures contract.
Because there is no expiry date, a perpetual contract needs a mechanism to keep its price from drifting too far away from the spot market it references. That mechanism is funding. Funding transfers value between long and short traders according to whether the contract is trading above or below the reference price. This is a core feature of perpetual futures, not a side detail, and it affects holding costs even when the market price appears unchanged over a short interval.
For a trader, the key point is that the quoted contract price is only one part of the picture. A position can gain or lose from price movement, incur funding payments, and face liquidation if margin falls too far. Understanding those three layers together is more important than focusing only on entry and exit price.
Index price, mark price, and trade price
The trade price is the price at which the last transaction in the contract occurred on the venue you are using. It is the most visible number on a screen, but it can be noisy. A brief burst of thin trading, a single aggressive order, or a temporary imbalance in the order book can move the trade price even when the broader market has not changed much.
The index price is a reference price built from the underlying asset’s broader market, often by combining prices from several spot venues or feeds. Its purpose is to estimate the asset’s external market value as robustly as possible. The exact construction varies by venue, but the economic role is consistent: the index price is meant to anchor the contract to the wider market rather than to one local order book.
The mark price is the internal pricing reference used for margining, unrealized profit and loss, and often liquidation checks. It is usually derived from the index price and may incorporate a funding basis or smoothing mechanism intended to reduce the effect of temporary spikes. This is important because liquidation decisions based only on the trade price could be triggered by a brief wick that does not reflect the broader market. The mark price is designed to reduce that risk, although it cannot eliminate it entirely.
A practical check is to ask three separate questions before acting: what is the last trade price, what is the current index price, and what price does the platform use for margin and liquidation? If those three differ materially, the difference itself is a trading risk signal. It may indicate volatility, thin liquidity, or a contract trading at a premium or discount to the underlying market.
Why funding payments exist
Funding is the periodic payment exchanged between longs and shorts in a perpetual contract. The purpose is not to create yield in the ordinary sense; it is to keep the contract price close to the index price. When the contract trades above the reference level, long positions typically pay short positions. When it trades below, shorts typically pay longs. The sign and size depend on the specific contract design, but the economic logic is consistent: the market side that is more crowded relative to the reference pays the other side.
This mechanism matters because a position can be profitable on price movement and still lose money once funding is included. For a trader holding for several funding intervals, the carrying cost can become a meaningful part of the outcome. Conversely, a position can lose on price movement but offset some of that loss through funding receipts, depending on direction and timing.
Funding is usually calculated on notional value rather than on initial margin alone. That means the cost can scale with position size, not just with the cash committed. A conservative way to think about it is that funding is an ongoing cost of maintaining exposure, not a one-time fee. Because rates can change over time, it is better to treat future funding as uncertain rather than to assume that a recent rate will persist.
A useful decision check is to estimate whether the expected holding period is long enough for funding to matter relative to your intended price thesis. If the trade idea only works if funding stays favorable, the position is more fragile than it may first appear. The same logic applies to hedges: a hedge that neutralizes price risk but accumulates funding cost may still be expensive to maintain.
Maintenance margin and the logic of liquidation
Initial margin is the amount required to open a position. Maintenance margin is the lower threshold that must be preserved to keep the position open. If account equity falls toward or below the maintenance requirement, the position becomes vulnerable to liquidation. In other words, liquidation is not primarily about the entry price; it is about whether remaining margin is sufficient to absorb further adverse movement plus any fees or funding obligations that may still apply.
A margin system is there to protect the market and the venue from losses that exceed posted collateral. Once equity is too low, the position may be reduced or closed automatically. The exact trigger depends on the contract rules, but the economic idea is straightforward: losses are tolerated only while enough collateral remains to support them.
It is important not to confuse unrealized loss with liquidation itself. A position may show a large unrealized loss and still remain open if margin is still above the maintenance threshold. Conversely, a relatively small additional move can be enough to cause liquidation when a position is highly constrained by margin. This is why traders often monitor margin ratio, maintenance requirement, and mark price together rather than watching only the entry price.
Another practical check is to ask how much adverse movement the position can absorb before maintenance margin is breached, after allowing for expected fees and possibly one or more funding periods. If the answer is difficult to estimate, the position may be operating too close to the edge for comfortable risk control.
Worked example: how price, funding, and margin can interact
Assume a hypothetical perpetual contract on an asset with an index price of 100. A trader opens a long position with a notional size of 10 units of the contract value. For simplicity, assume the contract is linear, fees are ignored, and the only costs are price movement and one funding payment. Also assume that the platform uses mark price rather than last trade price for liquidation checks.
Suppose the trade price at entry is 100.5 because the order book is slightly elevated above the index. A few hours later, the last trade price temporarily dips to 98 due to a brief sell-off, but the index price remains closer to 99.6 and the mark price is 99.7 after smoothing. If liquidation checks use the mark price, the position may not be treated as though it were at 98. This does not mean the trader is safe; it means the position is assessed against a more stable reference.
Now add funding. Assume the next funding interval requires longs to pay shorts 0.03% of notional. On 10 units of notional, the funding payment would be 0.003 units of the quote currency in this simplified example. That amount is small here because the notional is small and the hypothetical rate is modest. But the direction matters: even if the mark price later recovers to 100, the trader’s net outcome is still reduced by the funding payment.
Finally, imagine the maintenance margin requirement is 5% of notional and the trader posted 1 unit of collateral. If the mark-to-market loss plus fees plus funding reduce equity close to that 0.5-unit maintenance threshold, the position can be liquidated even before the trader feels that the market move is extreme. This example is intentionally simplified, but it shows the main point: the liquidation boundary is the result of several interacting inputs, not a single price on the screen.
The practical lesson from the example is to separate three questions. First, how far has the market moved relative to entry? Second, what does the platform’s mark price say about risk right now? Third, how much margin remains after funding and fees are considered? If any one of those answers is unclear, the position can be harder to manage than it appears.
Liquidation, partial liquidation, and ADL
When maintenance margin is no longer sufficient, the venue may liquidate part or all of the position. Some systems try partial liquidation first, reducing exposure to restore the account above the maintenance threshold. Others may move directly to a full close or use a liquidation engine that unwinds risk in steps. The exact process is venue-specific, but the purpose is the same: to prevent the account from owing more than the collateral can cover.
Liquidation is usually executed under stressed conditions, so the realized exit may differ from the liquidation trigger. That difference is one reason liquidation is costly. Thin liquidity, fast markets, and order book gaps can make the actual fill worse than the theoretical level implied by the mark price. Traders should therefore think of liquidation as a failure state, not as a neutral exit.
ADL, or auto-deleveraging, is another backstop used in some market structures. If the insurance or liquidation process cannot absorb a loss fully, profitable opposing positions may be reduced automatically. In practical terms, a trader with an open profitable position can be de-risked by the system even if that trader did nothing wrong. That is one reason ADL is usually treated as an exceptional mechanism rather than normal trade management.
A useful decision check is to look for signs that a position is entering a regime where liquidation or ADL becomes more plausible: sharply rising volatility, persistent adverse funding, widening differences between trade and mark price, or very low free margin. These are warning conditions, not predictions. The point is to identify when the system is doing more of the work of risk control because the position itself is less resilient.
Failure scenarios and the limits of the model
Perpetual futures often fail in ways that are easy to miss if a trader only watches the headline price. One failure scenario is a fast wick in the last traded price that does not reflect the broader market. If liquidation uses mark price, the wick may not matter much; if the mark price itself is stressed, the same move can become dangerous. Another failure scenario is funding accumulation over time. A position that is directionally correct can still become unattractive if repeated funding payments steadily erode equity.
A third failure scenario is gap risk in fast markets. Even a well-calibrated maintenance margin system cannot guarantee an exit near the theoretical threshold when liquidity disappears. A fourth is basis dislocation, where the perpetual contract diverges materially from spot for a period. In that case, a trader may be right about direction but wrong about the timing or path of convergence.
There are also limits to what the price references can do. The index price is only as robust as its constituent feeds and methodology. The mark price is only as good as the model behind it. Funding formulas can reduce but not eliminate crowding and premium/discount swings. ADL can protect the system, but it can also shift losses or exits to participants who did not choose to close. None of these mechanisms is perfect; they are trade-offs.
For that reason, a practical approach is to treat perpetual futures as a layered risk system rather than as a single instrument. Before entering a trade, check the price reference used for liquidation, estimate funding as a carrying cost, and ask whether the position still makes sense if liquidity worsens or funding changes sign. If the answer depends on assumptions that are fragile or hard to verify, the trade is less robust than it seems.
Jurisdiction and risk caveat
Perpetual futures may be restricted, unavailable, or treated differently depending on jurisdiction, account type, and venue policy. Legal, tax, and reporting consequences can also differ materially from one place to another. This article is educational only and does not address your local rules, suitability, or tax position. Because derivative products can move quickly and can be liquidated automatically, anyone considering them should understand the contract specifications, margin rules, and the risks of forced exit before participating.