> ## Documentation Index
> Fetch the complete documentation index at: https://docs.perpetradex.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Mark Price & Index Price

> The two prices behind everything on Perpetra

Perpetra uses two different prices for two different jobs. Mixing them up is a common source of confusion, so here's what each one actually does.

## Index price: the outside reference

The index price is Perpetra's read on what the asset is actually worth right now, based on outside sources rather than anything happening on Perpetra itself.

It's pulled primarily from Supra, with Chainlink as a backup. If both are available at the same time, the platform checks that they agree closely, and rejects the price if they've drifted too far apart from each other, that's a safety check against one provider glitching or lagging. When they do agree, Chainlink's value is the one used.

For assets that don't have reliable coverage from either of those providers, the index price instead comes from a live trading pool on SaucerSwap, paired against HBAR and converted into a USD value using HBAR's own price.

## Mark price: what the platform actually uses

The mark price is different. It isn't a direct read from any single outside source, it's a value the platform computes and pushes on-chain regularly (roughly every 30 seconds, or sooner if things move fast), blending the index price with the premium or discount showing up on Perpetra's own orderbook.

This is the price actually used for the numbers that matter to you day to day: your position's live value, your margin ratio, and whether a position is eligible for liquidation. See [PnL & Liquidation](/pnl-and-liquidation) for how those calculations use it.

## Why mark price exists at all

If positions were valued purely off the index price, someone could push Perpetra's own orderbook to an extreme price and force liquidations that have nothing to do with the real market. Mark price smooths that out by blending in the outside reference, so momentary spikes on Perpetra's own book don't directly translate into forced liquidations.

## Staleness protection

If the price-updating process stops running or falls behind, the mark price is only considered valid for a limited window. Once it's too old, the platform treats it as unavailable rather than using outdated data, which blocks trading on that market until fresh prices resume.