Mark Price vs Last Price in Crypto Futures: Stops and Liquidation

A futures chart can show one price while your position panel shows another. That is not necessarily an error. The chart may be showing the last price, while the exchange uses the mark price to assess liquidation risk. If you trade perpetual futures, you need to know which number each decision depends on.

On MEXC, the mark price is called the fair price. The distinction matters most when prices move quickly: your stop-loss and the liquidation system may be watching different prices.

What each price measures

Last price is the price of the most recent completed trade in a particular futures contract on the exchange. It tells you what just traded, not what your next order is guaranteed to receive. A thin order book or a sudden burst of trading can make it move sharply.

Mark price, or MEXC’s fair price, is a calculated reference used to value an open position for risk purposes. MEXC builds it using its spot-market index, futures-market information and the last price. It is designed to reduce the effect of an isolated spike in the futures order book; it is not a price at which you can place or fill a trade.

The index price is a third number: a reference assembled from prices on other spot markets. It helps inform the fair price but is not the same thing. On MEXC, the fair price governs liquidation, while actual entries and exits occur through the futures order book. (mexc.com)

An open position’s displayed unrealized profit or loss may use fair price by default, whereas realized profit or loss after closing depends on the actual fill and applicable costs. MEXC also allows users to change the displayed unrealized-PNL pricing basis in position settings. Changing that display does not change which price triggers liquidation. (mexc.com)

A worked example: the chart has not reached liquidation

Suppose you buy a BTCUSDT perpetual position equivalent to 0.5 BTC at 60,000 USDT per BTC. Later, the last price is 59,900 USDT, but the fair price is 59,600 USDT. Assume your position panel shows an estimated liquidation price of 59,500 USDT.

At those prices, the open loss measured against fair price is (59,600 − 60,000) × 0.5 = −200 USDT. Measuring against last price instead gives (59,900 − 60,000) × 0.5 = −50 USDT. Neither figure includes every possible trading cost. The gap explains why the position panel can look worse than a glance at the chart suggests.

Now imagine the fair price falls to 59,500 USDT while the last price remains at 59,800 USDT. Liquidation can be triggered even though a last-price chart has not printed 59,500. The reverse can happen too: a brief last-price wick through the liquidation level need not liquidate the position if fair price stays above it. These are illustrations, not predictions; the estimated liquidation level depends on the position’s margin and exchange rules. (mexc.com)

Why your stop-loss may behave differently

A stop-loss has a trigger price and an order that is submitted after that trigger. Neither is automatically the same as the liquidation reference. MEXC lets traders select last price, fair price or index price as a trigger for supported futures take-profit and stop-loss orders. Check the choice on the actual order you place rather than assuming a default. (mexc.com)

Return to the example. Suppose a sell stop for the long position is set at 59,700 USDT and watches last price. If last price is still 59,800 while fair price reaches the estimated 59,500 liquidation level, that stop has not triggered. Selecting fair price instead would make the stop watch the same type of price used for liquidation, but it would not guarantee an exit first. Prices can jump, liquidation levels can change, and orders can fail or fill only partly in a fast market.

A triggered stop is also not a fill at the trigger price. A market close takes the available prices in the order book and may suffer slippage. A stop-limit order controls its limit price but may not fill at all. MEXC warns that even its market-price TP/SL orders may fail or receive a different final fill during volatility. (mexc.com)

A pre-trade check that takes one minute

• Identify the price shown on your chart. On MEXC’s futures web interface, you can switch the chart display among last, index and fair price; the fair price is also shown near the trading pair. (mexc.com)
• Read the stop order’s trigger-price selection and confirm the order type and quantity. A level drawn using last-price candles may behave differently when monitored against fair price.
• Compare your planned stop with the position’s estimated liquidation price using the fair price, not only the chart’s last price. Leave room for changing margin requirements, funding and rapid moves; do not treat a narrow gap as protection.
• Size the position from the amount you can afford to lose at a plausible exit, allowing for slippage and trading fees. If the trade does not fit that risk budget, reduce its size rather than moving a structure-based stop closer just to make the numbers work. The position size calculator can help with the arithmetic.
• Check the contract’s funding rate and countdown if you might hold through settlement. MEXC commonly uses eight-hour funding periods, but the interval can differ by contract; funding is separate from both the stop trigger and the eventual fill price. (mexc.com)

Risk reminder: Leverage can turn a small price move into a large loss, and no stop-loss guarantees a particular exit price.

How Algentis uses this

Algentis scans the futures market, reads Smart Money Concepts structure across multiple timeframes, checks macro context and applies AI judgement before signalling a MEXC USDT perpetual trade. Its rules require a structure-based stop-loss, cap concurrent positions and include a daily-loss circuit breaker. A signal does not remove the need to check the exchange’s live price references, order settings and liquidation risk.