Skip to main content
Tplus tracks several price values per asset, each with a distinct role in margin, liquidation, and pricing. Every price carries its own decimal precision.

​
Oracle prices

An oracle service polls Chainlink, Pyth, and centralized-exchange (CEX) feeds, averages them, and publishes it to the clearing engine. Outliers are rejected, and an update whose source timestamp is more than 5 seconds from local time is rejected (a clock-skew guard). Prices are read through threshold RPC consensus — multiple independent endpoints must agree before a value is accepted. The feed-to-asset mapping is onchain and can only be rotated by a council-signed operation. See trust model.

​
Mark price

The mark price is an exponential moving average of last-trade prices, with a 45-second half-life. The last-trade price of a fill is the worst price across the matched makers — the highest for a buy taker, the lowest for a sell taker — so a single favorable print cannot drag the mark. It is not a TWAP.
Example: if the old mark is 100, the newest last-trade price is 110, and 45 seconds have elapsed, alpha = 0.5 and the new mark is 100 + 0.5 * (110 - 100) = 105. If a buy taker fills against makers at 100 and 102, the last-trade input is the worst fill for the taker: 102.

​
Impact price

The impact price is the volume-weighted price (VWAP) to execute a reference notional — 0.25% of the asset’s open-interest cap — against the book, computed separately for the buy and sell sides. Impact prices feed the premium component of funding rates by measuring how far executable book depth is from the oracle. They are not part of the normal IM/MM dual-price checks, which use oracle and mark.
Example: if the open-interest cap is 200,000,000 USD, the reference notional is 500,000 USD. If the ask side fills 100,000 USD at 100 and the remaining 400,000 USD at 101, the base filled is 100,000 USD / 100 + 400,000 USD / 101 = 4,960.396. The buy impact price is 500,000 USD / 4,960.396 = 100.80.

​
Dual-price checks

Margin and liquidation never rely on a single price:
  • Initial margin is the requirement to open or increase positions. Trade admission is checked at the oracle price and the mark price independently; IM surplus must be at or above zero for both.
  • Maintenance margin is the requirement to not be liquidated. Liquidation checks MM surplus under the dual-price rule and begins only when MM surplus is below zero.
If only one source is available it is used for both sides; if neither is available the check fails. See Margin.

​
Staleness and circuit breakers

Each source is tracked for freshness. Oracle prices go stale after 1 hour (sized to Chainlink heartbeats); mark and last-trade prices after 60 seconds. A stale source must deliver consecutive fresh updates before it counts as recovered, which prevents flapping. Prices past a 2-hour hard limit are never used. A newly listed asset, or one recovering after a restart, starts in a warming-up state that blocks risk-increasing trades until the oracle has delivered several consecutive fresh updates. When prices stop arriving, the asset’s price-state machine degrades: risk-increasing trades are blocked first, and if no usable price remains, the asset’s collateral is valued at zero and trading and liquidation halt for it. Full state table: Liquidations & circuit breakers.