Mark Price

Mark price is the reference price used to calculate unrealized PnL and trigger liquidations on perpetual futures positions. It is not the same as the last trade price. Mark price is constructed from the spot index of the underlying asset across major exchanges, with a small adjustment for funding, with the goal of preventing temporary manipulation of the perpetual price from triggering unfair liquidations.

Why mark price exists

On a thin order book, a large market order can briefly push the last trade price several percent away from the underlying spot price. If liquidations triggered on the last trade price, a manipulator could push the perpetual price down enough to liquidate longs, then let it snap back. Mark price defends against this by using a slower, manipulation-resistant reference: the spot index of the underlying asset, with a small adjustment for the funding rate. On Hex37, mark price tracks the Binance mark price for the relevant perpetual contract.

Mark price vs last price

Last price is the price of the most recent trade. Mark price is the reference price the exchange uses for liquidation calculations. On a liquid contract during quiet conditions, the two are usually within a fraction of a percent. During fast moves or thin liquidity, they can diverge by 1% or more. Your unrealized PnL on Hex37 is calculated against mark price, not last price, because mark is the reference the liquidation engine watches. This means your displayed PnL on a perpetual position may differ slightly from what you would see on a spot-style 'last price minus entry' calculation.

Where mark price matters most

Mark price matters at three moments: when calculating unrealized PnL, when triggering liquidations, and when settling funding (funding is calculated on mark price, not on last). For position monitoring during a fast move, the gap between mark and last is a useful signal: if last has dropped sharply but mark has not followed, the move may be temporary and a wider mark-tracking stop may avoid being shaken out.

What this changes for stop placement

• By default, stop-losses on Hex37 trigger against mark price, which protects against thin-liquidity manipulation.
• On highly volatile assets, mark price moves more smoothly than last price. Your stop is less likely to be hunted on a single wick.
• On manipulation-resistant assets (BTC, ETH on deep books), mark and last rarely diverge. The distinction matters mostly on thinner alts and meme coins.