Crypto glossary
Mark price vs last price
The mark price is the fair value a derivatives exchange uses to value positions and trigger liquidations, instead of the last traded price on its own book.
The last price is simply the price of the most recent trade on an exchange's order book. The mark price is a calculated reference, typically built from an index of spot prices across several venues plus a smoothed component of the contract's own basis or funding. Exchanges use it to compute unrealized PnL, margin ratios and the moment a position must be liquidated.
The separation exists to protect traders from manipulation and thin liquidity. Without it, a single large market order that briefly knocks the last price down could liquidate hundreds of leveraged longs even though the wider market barely moved. Every major perpetual venue, centralized or decentralized, shows both prices on the trading screen.
Traders sometimes see a wick on the chart that looks as if it should have hit their stop or liquidation level, yet nothing happens because the mark price never got there; the reverse can also occur. Mark price formulas differ by exchange, so the same position can have different liquidation levels on different venues.
Example
A flash sell order pushes the last price of a BTC perpetual down 3 percent for a few seconds, but the mark price, anchored to spot on five exchanges, drops only 0.4 percent and no long positions are liquidated.