Three Prices, One Liquidation: Mark, Index and Last Price Explained

Open any perpetual futures pair and three different numbers describe the same asset at the same moment. The last price fills your orders and draws the candles. The index price says what the asset is worth on spot markets elsewhere. The mark price decides whether your position survives. Traders who watch only the first one occasionally discover the third one exists at the worst possible moment.

This guide covers what each price is, how the major venues actually calculate them, why the gap between them opens during volatility, and the checks worth running before a leveraged bot goes live.

TL;DR

• Last price is the most recent executed trade on that venue's order book. It fills orders, draws charts and determines realized PnL.
• Index price is a weighted composite of spot prices across several external exchanges. It anchors the contract to the wider market and feeds funding calculations.
• Mark price is a fair-value estimate derived from the index. It drives unrealized PnL and triggers liquidation on most venues.
• Binance, Aster and EVEDEX all use a median-of-three construction: a funding-adjusted index, an index-plus-basis figure, and the contract's own last price.
• Hyperliquid builds its mark from an oracle price computed by validators from CEX prices, plus a 150-second EMA of its own basis, updated roughly every three seconds.
• Bybit applies a clamped blend of contract price and index price for a defined set of symbols, rolled out from November 2025.
• The practical consequence runs both ways: a wick on the chart may not liquidate you, and a position can be liquidated while the last-price candle still looks survivable.

What are mark price, index price and last price?

Three reference prices run in parallel on every perpetual futures contract. The last price is the most recent trade on that exchange's book. The index price is a weighted average of spot prices from multiple external exchanges. The mark price is a manipulation-resistant fair value calculated from the index, and it is what liquidation engines and unrealized PnL use.

Realized PnL is the exception worth remembering: when a position actually closes, the number that lands in your balance comes from the executed price, not the mark.

How index price is calculated

The index exists so that a single venue's order book cannot define the truth. Aster describes its price index as a weighted average across major spot markets including Binance, Huobi and Kraken, weighted so that higher-volume venues carry more influence (Aster docs). Binance uses the same principle for USDⓈ-margined futures, computing a price index from constituent spot exchanges before deriving anything else (Binance).

Two protections matter more than the weights. Aster removes any exchange that fails to update its feed within three seconds, so stale quotes cannot drag the index. It also applies last-trade-price protection: if the latest contract trade deviates more than 5% from the mark price and no new trade arrives within five seconds, the contract price is replaced by the current mark price in the calculation (Aster docs).

Hyperliquid takes a different route to the same goal. Its oracle price is a weighted median of centralized exchange prices computed independently by each validator and published roughly every three seconds, which means the reference does not depend on Hyperliquid's own market data at all (Hyperliquid docs).

How mark price is calculated, venue by venue

Most centralized venues and several perp DEXs share a common skeleton — take the index, adjust it two ways, and pick the middle value:

Mark price = Median (Price 1, Price 2, Contract Price)

• Price 1 = Index price × (1 + last funding rate × (time until next funding ÷ funding period))
• Price 2 = Index price + a short moving average of the basis, where basis is the order book mid minus the index
• Contract price = the venue's own last traded price

Binance samples its basis moving average over a 2.5-minute window built from 30 data points at five-second intervals, and notes that under abnormal conditions it may switch to using Price 2 outright as a protective measure (Binance). EVEDEX uses the same median-of-three shape with a five-minute basis average sampled every second (EVEDEX docs).

Hyperliquid's construction is different in kind. Its mark price is the median of three inputs: the oracle price plus a 150-second exponential moving average of the difference between Hyperliquid's mid price and the oracle; the median of best bid, best ask and last trade on Hyperliquid; and the median of Binance, OKX, Bybit, Gate.io and MEXC perp mid prices weighted 3, 2, 2, 1 and 1. If only two of those three inputs exist, a 30-second EMA of Hyperliquid's own bid/ask/last median is added as a fourth (Hyperliquid docs).

Bybit runs a clamped blend for a defined symbol set rolled out from November 2025: mark price = Price3 × C + index price × (1 − C), with C clamped between 0.3 and 0.7 based on the degree of mid-price deviation (Bybit).

The differences are not academic. A 150-second EMA and a 2.5-minute sampled average respond differently to the same 30-second spike, which means the identical strategy running on two venues has two different liquidation behaviors during fast moves.

Bitsgap connects Binance, Bybit, Aster, EVEDEX, Hyperliquid and other venues through one interface, so COMBO and DCA Futures bots can be configured, backtested and run in demo before a position is opened with real capital.

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Why you can be liquidated when the chart looks fine

Liquidation is triggered by the mark price reaching the liquidation price, not by the candle on the screen. Aster states it directly: forced liquidation occurs when the mark price reaches the liquidation price, and traders should monitor both (Aster docs). Bybit's help centre says the same for its contracts (Bybit).

That design protects traders in one direction and surprises them in the other.

The wick that does not liquidate you. A thin order book takes a large market sell, the last price drops 4% for two seconds, and the candle prints a long tail. Because mark price is anchored to a multi-exchange index and smoothed by a basis average, it barely moves. Positions that would have been closed by a last-price trigger survive. This is the scenario mark price was designed for.

The liquidation that arrives while the candle looks survivable. In the other direction, spot markets across the index sell off while this venue's own book lags, or the basis runs persistently negative. Mark sits below last, your position is valued on mark, and the engine acts on a number you were not watching. Nothing malfunctioned; the position was simply valued against a price you were not watching.

The gap widens exactly when it matters: thin liquidity, low-cap pairs, funding extremes and weekend hours. Aster's stock perpetuals documentation makes the point explicit by applying an exponentially weighted moving average to the last traded price during overnight, weekend and holiday sessions specifically to blunt thin-market spikes (Aster docs).

Five checks before a leveraged bot goes live

1. Read your liquidation price against mark, not against the candle. The distance that matters is mark-to-liquidation, and both numbers are shown on the position screen — on the exchange, and on any bot interface that surfaces them alongside the setup. On a pair where mark and last routinely sit 0.3% apart, a stop placed by eye off the chart is 0.3% further from where you think it is.
2. Check the current mark–last spread on your pair. Majors on deep books run tight. Long-tail pairs do not, and that spread is your error margin.
3. Know which reference your stop-loss triggers on — you probably did not choose it. Trigger price type for stop-loss and take-profit is set by the exchange, and bot platforms generally inherit that default rather than overriding it. So the reference your stop fires on is whatever your venue uses, and it may not be the one your liquidation runs on. Check the venue's order documentation once per exchange, not once per bot.
4. Recalculate after every safety order. DCA Futures and COMBO bots move the average entry with each fill, and the liquidation price moves with it. The number you checked at launch is stale by the third safety order.
5. Do not stack the stop next to liquidation. A stop placed a fraction below the liquidation price is not risk management; it is a slightly earlier liquidation with an extra fee attached. The mechanics of that gap are covered in crypto liquidations explained.

What this means for bot traders specifically

A bot places orders on the exchange. It does not stand between your position and the exchange's risk engine. When mark price reaches your liquidation level, the venue closes the position regardless of what the bot's logic intended to do next, and the bot's own stop-loss only helps if it sits meaningfully clear of that level.

Two consequences follow for anyone running futures automation across venues:

• Averaging strategies need liquidation tracking, not just stop placement. A COMBO or DCA Futures bot deliberately adds to a position as price moves against it. Each addition pulls the liquidation price closer to market. Sizing that assumed the launch-day liquidation distance is wrong by the time the ladder is half filled. Direction and structure decisions are covered in choosing COMBO direction before launch.
• The same settings behave differently on different venues. Mark price formulas, funding intervals and fee structures all vary. A configuration validated on one exchange is a hypothesis, not a result, on another — which is what demo mode and per-venue backtesting exist to test. Venue-level cost differences are broken down in the Aster trading fees guide and the Hyperliquid bots comparison.

Bitsgap runs COMBO and DCA Futures bots with configurable stop-loss and take-profit across connected exchanges, including Binance, Bybit, Hyperliquid, Aster and EVEDEX, and shows liquidation price and mark price on the bot screen so the gap stays visible while the position runs. Demo mode and backtesting are available before real capital is committed. Automation executes rules consistently; it does not remove leverage risk.

FAQ

What is the difference between mark price and last price? Last price is the most recent executed trade on a specific exchange's order book. Mark price is a calculated fair value derived from an index of external spot prices plus a basis or funding adjustment. Last price fills orders; mark price drives unrealized PnL and triggers liquidation.

Which price triggers liquidation in crypto futures? Mark price. Major venues including Binance, Bybit, Aster and EVEDEX use mark price rather than last traded price for liquidation, which reduces the impact of temporary order book spikes and manipulation on a single venue.

What is index price in perpetual futures? Index price is a weighted average of an asset's spot price across several external exchanges. It anchors the perpetual contract to the wider market, feeds funding rate calculations, and serves as the base input for mark price.

How is mark price calculated on Binance? Binance takes the median of three values: the price index adjusted by the last funding rate scaled to time until next funding, the price index plus a 2.5-minute moving average of the basis, and the contract's last traded price.

How does Hyperliquid calculate mark price? Hyperliquid uses the median of three inputs: its validator-computed oracle price plus a 150-second EMA of the difference between Hyperliquid's mid price and the oracle, the median of its own best bid, best ask and last trade, and a weighted median of perp mid prices from Binance, OKX, Bybit, Gate.io and MEXC.

Why is mark price different from the price on the chart? Charts typically plot last traded price from that venue's own book. Mark price is smoothed and anchored to external spot markets, so during volatility, thin liquidity or funding extremes the two diverge. The gap is largest on low-liquidity pairs and during off-peak hours.

Can a stop-loss trigger on mark price? That depends on the exchange, not on the trader. Each venue defines which reference its stop-loss and take-profit orders trigger on, and bot platforms typically inherit that default. Since liquidation runs on mark price regardless, the practical step is to check what your exchange uses and leave a wider buffer where the two differ.

Does mark price affect realized profit and loss? No. Mark price determines unrealized PnL and liquidation. Realized PnL is calculated from the actual execution price when the position closes.

Which price is used for funding payments? Funding calculations are anchored to the index or oracle price rather than the venue's last traded price, so that a distorted local order book cannot inflate funding costs.