Why perpetual futures show two prices
Mark price vs last price is one of the most important distinctions in perpetual futures trading — and one of the least explained. Most new traders assume the price shown on their chart is the price that matters for everything. It is not.
Perpetual futures platforms display two separate prices simultaneously:
- ·Last price — the most recent trade executed on that exchange
- ·Mark price — a calculated fair value derived from multiple external sources
Understanding which price controls which function — and why — directly affects how you set stops, how you read your unrealized PnL, and whether your liquidation price is what you think it is.
New to perps? Start here → What Are Perpetual Futures?
What last price is
Last price is exactly what it sounds like: the price at which the most recent trade was executed on that specific exchange's order book.
Last price is what you see on the candlestick chart. It reflects real supply and demand on that exchange — but only that exchange. If a large market order moves the order book on one exchange, the last price spikes even if the broader market (across all exchanges) barely moved.
Last price is used for:
- ·Candlestick charts and price history
- ·Most stop loss and take profit order triggers on most exchanges
- ·The reference price for most technical analysis
The problem with using last price for everything: it can be manipulated. A coordinated large order or a liquidity vacuum can spike last price briefly — long enough to trigger stop losses or liquidations — without reflecting any real change in the broader market price of the asset.
What mark price is
Mark price is a fair value calculation designed to be resistant to manipulation on any single exchange. It is derived from a combination of:
- ·The spot price index — an average of the asset's price across multiple major spot exchanges
- ·A funding rate basis component — reflects the relationship between the perpetual contract and spot
- ·Sometimes an exponential moving average — smooths out short-term spikes
The exact formula varies by exchange, but the principle is consistent: mark price tracks the broader market value of the asset, not just the activity on one exchange's order book.
Mark price is used for:
- ·Calculating unrealized PnL on open positions
- ·Determining liquidation price
- ·Calculating margin requirements
Which price triggers liquidation
Liquidation is triggered by mark price — not last price. This is the most important practical consequence of the mark price / last price distinction.
What this means in practice:
- ·A spike in last price — caused by a large order, a thin order book, or manipulation — cannot liquidate your position if mark price did not move
- ·Conversely, if mark price moves against your position but last price has not yet caught up, your position can approach liquidation even though the chart looks fine
This is why reputable exchanges use mark price for liquidation — it protects traders from being liquidated by temporary, exchange-specific price anomalies that do not reflect real market moves.
How liquidation is calculated → The Math of Perpetual Futures Liquidation
Why mark price prevents manipulation
Before mark price became the standard, exchanges using last price for liquidation created an obvious attack vector: a large trader could place coordinated orders to briefly spike or crash the last price on a single exchange, triggering mass liquidations, then reverse the position and profit from the liquidation cascade.
This was not a theoretical concern. It happened repeatedly on early crypto derivatives platforms.
Mark price eliminates this attack vector. To move mark price, an actor would need to simultaneously move the spot price across multiple major exchanges — a far more difficult and expensive operation. Manipulation of a single exchange's order book no longer affects liquidations.
For retail traders, this means:
- ·Liquidations reflect real market moves, not exchange-specific anomalies
- ·Stop loss hunters targeting last price cannot trigger your liquidation
- ·Temporary wicks on your exchange's chart do not put your position at risk if broader market price holds
How this affects your stop loss
Here is where it gets practical: most exchanges trigger stop loss orders based on last price, not mark price. This means:
- ·Your stop loss can be triggered by a last price wick even if mark price never reached your stop level
- ·Your liquidation cannot be triggered by a last price wick if mark price held
The implication for stop placement: stops set too tight are vulnerable to last price wicks — brief, sharp moves that snap back immediately. If your stop is within the typical wick range of the asset, you will be stopped out of valid trades by noise.
Using volatility-based stop placement (1.5× ATR from entry) provides a buffer that accounts for typical wick depth. A stop placed outside the noise range is less likely to be triggered by last price anomalies that do not reflect real market direction.
Some exchanges offer the option to trigger stop losses based on mark price rather than last price. If this option is available and your strategy involves tight stops, mark-price stops reduce false stop-outs from wicks.
Stop loss placement guide → How to Set a Stop Loss in Perpetual Futures
What to check before every trade
Three mark price checks before entering any perpetual futures position:
- 1.Check mark price vs last price divergence. If they differ by more than 0.5%, the market is in a volatile or illiquid state. Factor this into your stop placement — wicks are more likely during divergence.
- 2.Verify your displayed liquidation price uses mark price. Look at your exchange's position panel after opening. The liquidation price displayed should be calculated from mark price — if the exchange documentation says otherwise, account for that in your leverage decision.
- 3.Read unrealized PnL from mark price, not last price. If your chart shows a favorable last price but your PnL is flat or negative, mark price has diverged. Do not make exit decisions based on the chart alone.
The complete risk management framework → Perpetual Futures Risk Management
How to evaluate exchange liquidation mechanics → How to Choose a Perpetual Futures Exchange