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A perpetual (“perp”) is a futures-style contract with no expiry. Because it never settles, OCX uses two distinct prices to keep it tethered to the real market — the index price and the mark price — plus a periodic funding mechanism that economically links the perp to its underlying.

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Index price

The index price is OCX’s estimate of the perpetual’s fair underlying value. Rather than reading a single spot quote, OCX derives the index from the CME futures curve for the underlying. In practice this means the index tracks the front-month futures contract, and as that contract approaches expiry OCX gradually rolls the index toward the next contract. The roll is smoothed over a window so the index transitions continuously from one contract to the next instead of jumping on a single day. The index is the “honest” number: it comes only from external exchange data and never from OCX’s own order book, so it cannot be manipulated by activity on OCX itself.

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Mark price

The mark price is the price OCX uses to value open positions, compute unrealized PnL, and trigger liquidations. It is anchored to the index price but is allowed to follow OCX’s own order-book mid when the book is healthy and the mid sits close to the index. If the OCX book is thin, one-sided, or has drifted away from fair value, the mark stays on the index. This design keeps the mark responsive to genuine OCX price discovery while preventing a sparse or manipulated local book from dragging position values away from reality. Because the mark is a smoothed value rather than the raw last trade, it protects traders from liquidations caused by momentary wicks or single prints.

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Funding

Funding is the mechanism that keeps a perpetual’s price aligned with its underlying index over time. It is a periodic cash flow exchanged directly between long and short position holders — OCX does not take a side.
At each funding interval, the funding rate is applied to the notional value of every open position. Depending on the sign of the rate, longs pay shorts or shorts pay longs.
When the perp trades at a premium to the index (mark above index), the rate is positive and longs pay shorts, which incentivizes selling and pushes the perp back down toward the index. When the perp trades at a discount (mark below index), the rate is negative and shorts pay longs, pushing it back up. A small interest component reflects the cost of carry.
Funding accrues and settles on a fixed schedule (a recurring interval), not continuously. Only positions open at a funding timestamp participate in that period’s exchange.
The rate is clamped to a maximum magnitude in each direction, so a temporary dislocation between mark and index can never produce an unbounded funding payment.
Conceptually, the funding rate moves with the premium of the perp over its index, plus an interest term: funding rate  ∝  mark−indexindex  +  interest\text{funding rate} \;\propto\; \frac{\text{mark} - \text{index}}{\text{index}} \;+\; \text{interest} The current per-market mark price, index price, and funding rate are published through GET /perps/market-stats, so you can always see the live inputs.