Three prices

Your exit is not the ticker because liquidation and P&L use the venue's mark price, a fair-value estimate. The last trade on the ticker can differ by hundreds of dollars in volatile minutes.

◇ THE MECHANIC

On a perp venue you see at least three prices:

• Last trade: the most recent price someone paid. It shows sentiment and fills. Risk systems ignore it.
• Mark price: the exchange's fair-value estimate. Unrealized P&L and liquidation checks use it.
• Index price: aggregated spot from external venues. It anchors mark and funding.

They diverge when liquidity thins, one venue moves first, or a fat-finger print hits the tape. Social media shows last. Your account uses mark. Venue mark methodology matters when slippage widens.

Primary source: Hyperliquid robust price indices define how mark, oracle, and external feeds combine.

◇ THE PURPOSE

Last price is easy to manipulate in thin markets and lags during gaps. Mark smooths wicks so liquidations reflect sustained moves, not a single bad print. Index anchors mark to spot across major venues. Funding (Lesson 03: the transfer between longs and shorts keyed off index and mark) uses both to pull the perp back when it drifts.

◇ THE RISK

You set a mental stop at $67,000 because "price" touched it on another app. Your position used mark at $67,380. That is deeper underwater than the ticker suggested. A spike through your liquidation level on last alone may not liquidate you if mark did not follow.

◇ WORKED EXAMPLE

Last $67,450 · Mark $67,380 · Index $67,400: which liquidates you?

−$182 unrealized P&L on mark, not −$162 on last

You are long $20,000 notional entered at $68,000. Price dumps. On the tape:

Price	Level	Role
Last	$67,450	What Twitter shows
Mark	$67,380	What your unrealized P&L uses
Index	$67,400	Spot anchor

Unrealized P&L uses mark: ($67,380 − $68,000) / $68,000 × $20,000 ≈ −$182. Using last would show −$162. That is $20 less pain, but not what the venue books.

Liquidation triggers on mark, not last. A one-second wick to $66,900 on last did not kill you if mark stayed at $67,380. Risk systems ignore the screenshot price.

When mark and index separate, funding often intensifies to pull the perp back. That is the mechanism working, not a platform bug. For risk, trust mark. For sentiment, last is enough.

◇ RECAP

• What are you holding? Exposure marked at fair value, not the last print.
• What do you pay while holding? Funding keyed off index and mark (Lesson 03: the recurring transfer between longs and shorts).
• What forces you out? Mark crossing your liquidation threshold, not necessarily last (Lesson 04: maintenance breach closes the position automatically).
• When is a perp wrong? When you cannot tolerate mark-to-market vs ticker confusion (Lesson 06: long horizons with hostile funding).