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Mark Price

A mark price is a venue-defined reference used for derivatives risk accounting. Learn how it differs from index and last prices, how venues calculate it, and where its protections can fail.

Updated

For educational purposes only; not investment advice. Crypto derivatives are leveraged products and can cause rapid, substantial losses.

Direct answer

A mark price is a trading venue’s calculated reference price for valuing an open derivatives position and applying risk rules. Depending on the contract, it may drive unrealized profit and loss, position value, margin requirements, and liquidation checks. Its purpose is to reduce the effect of a brief, illiquid, or manipulated trade on those calculations.

The mark price is not necessarily executable. The last price is the most recent matched trade on the contract’s order book; the index price represents an external underlying market under a separate methodology; the mark price usually starts from that index and adds a controlled estimate of the contract’s premium, discount, or funding basis. Realized profit and loss normally depends on actual entry and exit fills or the specified settlement price, not on an assumed fill at the mark.

There is no universal formula. Bybit, OKX, BitMEX, and Deribit document different inputs, smoothing windows, medians, caps, and fallback modes, and rules can also differ between perpetuals, dated futures, options, and pre-launch products. The contract specification and the venue’s current methodology control.

How it works

  1. Choose the underlying reference. The venue identifies an index or other external reference, its timestamp, and the contract to which it applies. Any weakness in the index can pass into the mark.
  2. Estimate the contract basis. The method may use a decaying funding basis, a moving average of contract mid-price minus index price, impact prices, option-implied information, or a combination. A useful abstraction is M_t = I_t + B_t, where M_t is mark price, I_t is index price, and B_t is the venue-defined basis adjustment.
  3. Apply stabilizers. A venue may use medians, time weighting, clamps, price bands, or limits on how quickly the basis changes. These controls reduce sensitivity to isolated prints but can also make the mark lag a genuine fast market.
  4. Handle exceptional states. Missing or distorted index inputs may activate another formula, protected last-price mode, estimated opening price, or other fallback. A fallback can be less independent than the normal method.
  5. Feed risk calculations. The resulting mark may update unrealized P&L, notional value, initial or maintenance margin, and the liquidation engine. Exact dependencies vary by margin mode and product.
  6. Keep execution separate. Market and limit orders still execute against available orders. A stop can be configured to trigger from mark, index, or last price on some venues, but its eventual fill depends on the order book.

Worked example

  • Suppose the index price is $100,000 and the venue’s allowed basis adjustment is +0.20%. Under the simplified relationship M_t = I_t x (1 + b_t), the mark price is $100,200.
  • A thin last trade at $98,000 does not by itself change that calculation. A long position may therefore show risk and unrealized P&L near $100,200, even though the latest candle printed $98,000.
  • If the trader submits a market sell, the position closes against bids, not at the mark. An average fill of $99,700 determines realized price P&L under the contract rules, with fees and funding added separately.

This example is illustrative, not a venue formula. Before relying on any displayed distance to liquidation, verify the actual basis inputs, update cadence, caps, fallback state, margin mode, fee treatment, and trigger-price setting.

Risks

  • Index risk: stale, unavailable, misweighted, or distorted constituents can move the reference itself.
  • Basis-model risk: smoothing and caps can lag real repricing or preserve an obsolete premium or discount.
  • Fallback risk: when external data fails, a venue may depend more heavily on its own last price or order book.
  • Liquidation risk: a position can be liquidated when the mark reaches the threshold even if the last-price chart does not.
  • Execution risk: the mark is not liquidity; spreads and slippage can make the exit materially worse.
  • Trigger mismatch: a stop watching last price may not fire before a mark-price liquidation, or the reverse.
  • Rule-change risk: venues can revise formulas, eligible products, intervals, caps, and emergency procedures.
  • Platform and leverage risk: calculation protections do not remove outages, custody exposure, funding costs, or losses amplified by leverage.

Keep a buffer between the current mark and the liquidation threshold, monitor both mark and executable prices, and stress-test a simultaneous index disruption, wider basis, and thinner order book. A smoother reference reduces one failure mode; it does not make a leveraged position safe.

Common misconceptions

  • “Mark price is the price where I can close.” It is an accounting and risk reference; execution occurs against orders or a settlement rule.
  • “Mark price and index price are the same.” The index is commonly an input, while the mark can include basis, funding, smoothing, or protection logic.
  • “A mark price prevents liquidation manipulation.” It can reduce sensitivity to one local trade, but its inputs, model, and fallback can still fail or be influenced.
  • “If the chart never touched my liquidation price, liquidation was wrong.” The chart may show last-price candles while the contract uses mark price for liquidation.
  • “All exchanges calculate it the same way.” Methodologies and product rules differ and can change; read the current specification for the exact contract.

Sources

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