Perpetuals

A perpetual future tracks the price of an asset without ever settling to a delivery date. You post margin, choose long or short, and the position gains or loses with the asset's price for as long as you hold it.

Two mechanisms make that work:

• Leverage sets how large a position your margin controls. With 20× leverage, $1,000 of margin controls a $20,000 position. See Margin and Leverage.
• Funding is a small hourly payment between longs and shorts that keeps the perpetual's price tied to the real market. See Funding.

Mark and index

• The index price is the reference price of the underlying asset, from the oracle.
• The mark price is the price the exchange uses to value positions, compute margin and trigger liquidations. It is the index adjusted by the order book's premium — the average gap between the book's impact price and the index over the current funding hour — clamped so it can never drift more than a fixed percentage of the index.

Valuing positions at the mark rather than the last trade means a single thin fill cannot liquidate anyone.

Profit and loss

Unrealised P&L is the difference between the mark and your entry price, times your size. It moves your equity continuously; it is realised when you close the position, and it settles in USDλ.