OCT 23, 2026
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On spot there is one price. On a perp I am reading four: the last traded price, the index price, the mark price and, once I am in a trade, a liquidation price. This lesson is how I read them before I size a position, using Aevo’s own definitions.
IN THIS LESSON
Spot has one price. A perp has a traded price, an index price, a mark price and a liquidation price.
The index is Aevo’s composite of spot prices. Funding pulls the perp towards it, and funding is charged on it.
The mark price is the median of three prices, built so one thin order cannot set it.
The liquidation price is an estimate. It moves with your margin, your collateral and your other positions.
01
One price on spot, four on a perp
On a spot market I look at one number and I own the asset or I don’t. On a perp I read a small dashboard before I place anything. The four prices below answer four different questions, and mixing them up is where most of the avoidable surprises come from.
Price
What it is
The question it answers
Spot price
The last trade on a spot market
What does the asset cost to own?
Traded price
The last trade on Aevo’s perp order book
Where am I likely to be filled?
Index price
Aevo’s composite of spot prices
What is the perp anchored to?
Mark price
The median of fair price, price 1 and price 2
What is a fair reference for my position?
Liquidation price
An estimate of where equity falls to maintenance margin
Where does the trade stop being mine?
The first thing I do on a perp ticket is compare traded price against index. If I only watched the traded price I would be reading the one number a single order can move.
02
Index price: what the perp is anchored to
Aevo builds its index from spot prices on several centralized exchanges. It leaves out sources that are disconnected, switched off or sending invalid data, finds the median of the rest, removes any pair that has drifted more than 0.5% from that median, and takes the mean of what is left. For ETH the constituents are Coinbase, Binance, OKX, Bitget, Bybit, Huobi, Gate, Bitfinex, Kraken and Bitstamp, equally weighted, and the index tracks the ETH/USDC pair.
Two things follow, and I keep both in mind. The index moves with the spot market, not with Aevo’s own order book, and funding is measured against it. When the perp trades above the index, longs are paying for the privilege of holding it.
03
Mark price: three prices, take the middle
Aevo’s documentation defines the mark price of a perpetual as the median of three numbers:
Fair price. The midpoint of a fair impact bid and a fair impact ask. The impact bid is the average price of a $10,000 notional market sell, and the impact ask is the average price of a $10,000 notional market buy. For BTC and ETH the figures are bounded by the best bid or ask plus or minus 0.1%.
Price 1. The index price multiplied by one plus the last funding rate times the hours until the next funding payment.
Price 2. The index price plus a 5-minute moving average of the difference between the fair price and the index.
The docs give a simple case. With an index of 2,000, a last funding rate of 0.005 and half an hour to go, price 1 is 2,000 × (1 + 0.005 × 0.5) = 2,005.
I like the median because it is hard to push. One thin order book, one odd print or one stale input can distort a single number, but it cannot drag the middle of three. When Aevo has to close positions against a bankrupt account in auto-deleveraging, the docs say it does so at the mark price, which is a good sign of which number the exchange trusts.
04
Funding: the rope between perp and spot
A perp has no expiry, so something has to keep it near spot. That something is funding, a payment between longs and shorts, paid every hour. Aevo does not take a fee on it. The docs build the rate from an average premium index, sampled every 5 seconds, plus a clamped interest term, then cap it and divide an 8-hour figure down to an hourly one.
In calm markets the premium stays within a narrow band and the rate sits at the fixed interest rate of 0.01% per 8 hours for most assets. That is 0.00125% an hour. On a $10,000 position it is about $0.125 an hour, or roughly $3 a day, paid by longs when the rate is positive and by shorts when it is negative.
The tail is what I plan for. The docs’ worked example has a BTC funding cap of 3% per 8 hours, which is 0.375% an hour. An 8 BTC long with the index at 15,000 would be charged 450 USDC for that hour. Funding is valued at the index price, not the mark.
05
Liquidation price: an estimate, not a promise
Aevo’s liquidation engine evaluates the whole account. In the docs the test compares your account balance, less the value of open orders, against the maintenance margin of your positions. When that test fails the account is taken over: open orders are canceled, short positions are reduced on the order book in steps, then against the insurance fund, and as a last resort through auto-deleveraging. A liquidation fee applies, 1% of the liquidated position value on BTC and ETH perps.
For BTC and ETH perps the parameters are 5% initial margin (20x maximum) and 3% maintenance margin. In a simplified isolated model with an entry price of 100, a long is liquidated at roughly 100 × (1 − 1/leverage + maintenance margin). At 10x that is about 93, and at 20x about 98. The leverage and margin lesson has a calculator for it.
What I remember is that the number on the ticket is not fixed. On a cross margin account it depends on every other position and on the collateral behind them, and ETH or WBTC posted as collateral counts at a haircut and falls in value when the market does. See how cross margin perps & options work together before relying on a single liquidation figure.
06
Put the four prices together
This explorer builds the mark price the way Aevo’s documentation describes it, then shows what that means for a position. Move the sliders and watch which of the three inputs ends up as the median.
From index price to mark price to liquidation
The median of the three inputs is price 2. Move one input a long way and the mark barely follows, because it only takes the middle value.
Illustrative. The mark price follows the formula in Aevo’s documentation, with the fair price approximated as the index plus your premium. The liquidation estimate is the simplified isolated model with 3% maintenance margin and ignores fees and funding, so it is a guide to the shape and not a quote.
07
What I check before I place a perp order
I put traded price, index price and mark price side by side. A wide gap between traded and mark tells me the book is thin or moving fast.
I check the funding rate and how long until the next payment, and I work out what holding the position costs per day.
I read the liquidation estimate on the margin mode I am actually using, then compare it with the price where I would exit anyway. I want my exit well inside it.
I size so that a normal move in the market does not threaten the position, instead of sizing to the maximum leverage on offer.
If I am adding an options hedge, I look at what it does to the margin requirement. Portfolio margin explains why a hedged book can need less.
Which price does Aevo use to value a funding payment?
The documentation states that the USDC value of funding uses the index price and the position size, not the mark price.
How is the mark price built?
Averaging spot prices from exchanges describes the index. The mark price takes the middle of three inputs so that one distorted number cannot set it.
WHERE TO GO NEXT
Trading leveraged contracts with no expiry? Aevo runs a perps dex with on-chain settlement and 20x on BTC and ETH. Browse every crypto perpetual markets on Aevo with live mark and index prices. Every cost of a trade, from maker and taker fees to funding and liquidation, is in the fees lesson. New to derivatives? The crypto derivatives guides take you from your first perp to hedging in seven short lessons.
08
Frequently asked questions
What is the difference between mark price and last price?
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What is the Aevo index price made of?
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How often is funding paid on Aevo?
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Which price is funding charged on?
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Is my liquidation price the same as the mark price?
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Why does my liquidation price change while I hold a position?
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Put the lesson to work
Practice on testnet or start small on mainnet.
Launch Exchange ↗
LEVEL
BEGINNER
TIME
10 MINUTES
PRIOR KNOWLEDGE
NONE
WORKED EXAMPLES
ILLUSTRATIVE
LEARN / PRICES / MARK PRICE / LESSON 1
This lesson is for education only and isn’t financial advice. The first-person habits described here are one way to read perp prices, not a recommendation and not a record of results. Leveraged products can lose more than you expect, quickly. Worked examples are simplified and use illustrative numbers.