Why is the price mark on Bybit different from the last traded price?

Price Mark Mechanism on Bybit

1. Bybit uses a mark price rather than the last traded price to calculate unrealized P&L and determine liquidation events. This design prevents manipulation during volatile market conditions.

2. The mark price is derived from a composite of several spot exchange indices, weighted by trading volume and reliability. It reflects broader market consensus instead of isolated order book activity.

3. Bybit’s algorithm incorporates funding rate decay into the mark price calculation for perpetual contracts. This adjustment ensures alignment between perpetuals and underlying spot markets over time.

4. During extreme volatility, Bybit applies fair price deviation filters to cap the distance between mark price and index price. These filters activate only when abnormal spikes or gaps occur in real-time data feeds.

5. The mark price updates continuously, often with sub-second latency, while the last traded price depends solely on executed trades—making it inherently lagging and more susceptible to thin liquidity or wash trading.

Index Price Composition

1. Bybit selects major spot exchanges such as Binance, Coinbase, Kraken, and OKX to construct its index. Each exchange contributes based on real-time bid-ask depth and 24-hour volume weighting.

2. Exchanges undergo periodic review for data integrity. If an exchange reports stale prices, abnormally wide spreads, or fails health checks, its weight is reduced or temporarily excluded.

3. The index price is calculated as a median—not average—to reduce outlier impact. A single exchange reporting a deviant value does not skew the overall index significantly.

4. Time-weighted sampling ensures that older data points decay in influence, prioritizing freshest available quotes across all sources.

5. Index updates are timestamped and logged publicly via Bybit’s API endpoints, allowing traders to verify inputs independently.

Liquidation Triggers and Risk Management

1. Liquidation occurs when a position’s margin balance falls below maintenance margin relative to the mark price—not the last traded price. This avoids premature liquidations caused by flash crashes or spoofing.

2. Bybit implements partial liquidation for large positions, using tiered margin requirements tied directly to the current mark price level.

3. The insurance fund absorbs losses from auto-deleveraging only after mark-price-based liquidations fail due to insufficient counterparty interest.

4. Traders receive margin call alerts when equity drops to 110% of maintenance margin, calculated dynamically against live mark price streams.

5. Negative balance protection remains active regardless of mark price divergence, ensuring users cannot owe funds beyond their initial margin deposit.

Funding Rate Influence on Mark Price

1. Funding payments are exchanged every eight hours between long and short holders based on the difference between mark price and index price.

2. When the mark price exceeds the index price consistently, positive funding rates accrue—encouraging shorts to enter and pulling the mark price back toward equilibrium.

3. Bybit applies a smoothed funding rate multiplier in the mark price formula, preventing step-function jumps during funding settlement windows.

4. Historical funding data is accessible through Bybit’s public REST API, enabling third-party tools to reconstruct mark price behavior over time.

5. The funding component decays linearly over the funding interval, meaning its influence peaks at the moment before settlement and diminishes immediately afterward.

Frequently Asked Questions

Q: Does Bybit ever override the mark price manually?Bybit does not intervene manually. All adjustments follow pre-defined, open-sourced logic published in its documentation. No human operator modifies the mark price in real time.

Q: Can I see the raw index components feeding into the mark price?Yes. Bybit provides real-time access to individual exchange prices, weights, and the final composite index via its Market Data API under the /v5/market/index-price endpoint.

Q: Why doesn’t Bybit use only the last traded price for margin calculations?Using only the last traded price would expose users to manipulation through low-volume trades, intentional slippage, or illiquid order books—undermining fairness and systemic stability.

Q: How often is the mark price updated?The mark price refreshes every 200 milliseconds during normal operation. During high-load periods, update frequency remains consistent but may reflect minor latency increases in data ingestion pipelines.