Notice: Understanding Index Price, Mark Price, and Last Price in Futures Trading

Introduction

When trading futures on BloFin, you may notice three different prices:

• Index Price
• Mark Price
• Last Price

Although these prices may appear similar, each serves a different purpose in trading, risk management, and order execution. Understanding the differences helps you better interpret your positions, liquidation risk, and profit and loss (PnL).

1. What is Index Price?

Index Price is a weighted average of spot prices collected from multiple major cryptocurrency exchanges.

It serves as the market reference price and helps ensure fair pricing by reducing the impact of abnormal price movements on a single exchange.

Main uses

• Reference price for futures contracts
• Basis for calculating Mark Price
• Determines the allowable price range for limit orders
   

2. What is Mark Price?

Mark Price is the estimated fair value of a futures contract.

Rather than using only the latest traded price, Mark Price combines:

• Index Price
• Funding basis
• Other pricing mechanisms

This helps reduce unnecessary liquidations caused by temporary price spikes or market manipulation.

Main uses

• Liquidation
• Margin ratio calculation
• Unrealized PnL calculation
   

3. What is Last Price?

Last Price is the price of the most recent trade executed on BloFin Futures.

Since it reflects actual trading activity, it changes continuously as users buy and sell contracts.

Unlike Mark Price, Last Price can fluctuate significantly during periods of high volatility.

Main uses

• Executing trades
• Triggering TP/SL orders (assuming BloFin uses Last Price as configured in the current FAQ)
• Realized PnL calculation

4. Comparison

5. Why are there different prices?

The Last Price can temporarily deviate from the underlying market due to buying and selling activity.

If liquidation relied solely on the Last Price, users could be unfairly liquidated during brief periods of extreme volatility or low liquidity.

Using the Mark Price helps provide a more stable and fair reference for risk management. This is the same rationale described by other major exchanges, including Binance,OKX, Bybit and Bitget.
 

6. Common Questions

Why was I liquidated even though the K-line didn't reach my liquidation price?

Liquidation is triggered using the Mark Price, not the Last Price shown on the K-line.

Why didn't my TP/SL trigger?

TP/SL orders are triggered according to the selected trigger price type. If your order uses Last Price, it will trigger only when the Last Price reaches your trigger price.

Why is my unrealized PnL different from the market price?

Unrealized PnL is calculated using the Mark Price, while realized PnL is based on the execution price of completed trades.

Why are prices slightly different across exchanges?

Each exchange uses different index constituents and calculation methodologies. Small differences in Index Price, Mark Price, and Last Price are normal.