Binance Retires TACUSDT Price Shield, Restores 2% Funding Cap

Binance Futures ended its Last Price Protected period for the USDⓈ-margined TACUSDT perpetual on September 7, returning liquidations to a multi-input mark price while reopening funding to a ±2% cap. The transition began at 06:00 UTC and could take up to three hours; trading continued and Binance said it would not cancel open orders or positions.

What changed inside TACUSDT’s mark-price path?

A TACUSDT market buy still matches against Binance’s futures order book, so the fill and realized profit or loss come from executed contract prices. What changed happens after the fill: the mark used for unrealized PnL and liquidation no longer relies on the emergency LPP calculation.

Binance introduced LPP on August 27 after observing TAC spot-price divergence across exchanges. During that period, its engine recalculated the mark every second from the average of the previous 10 seconds of TACUSDT trades. If that window held fewer than 21 trades, it widened the sample to 100 seconds when possible, otherwise using the last 100 trades. A ±1% per-second change limit constrained the result, and Binance Futures was the index’s only component.

The restored formula takes the median of three values: a spot index adjusted for time to funding, the index plus a 30-second order-book basis, and the contract price. Binance’s mark-price methodology says the spot index is a weighted composite of eligible venues. That middle-value selection rejects an extreme input instead of letting one thin contract tape define liquidation marks.

How much funding risk returned?

The cap moved from ±0.005% under LPP to ±2% under the standard rules—a 400-fold increase. On a 10,000 USDT position held through a settlement, the maximum transfer therefore rises from 0.50 USDT to 200 USDT; which side pays depends on the funding rate’s sign. Those are ceilings, not a claim that TACUSDT settled at either rate.

The schedule in Binance’s September 7 notice kept the 04:00 UTC settlement at ±0.005% and showed ±2% from 08:00 UTC onward. If a settlement reaches the new cap or floor, the next interval can shorten from four hours to one, increasing how often an exposed position can transfer funding.

Does the change improve execution?

Yes—for liquidation integrity, not carrying cost. Reintroducing independent spot inputs is a better defense against a venue-specific futures print now that Binance says a stable index is available. The trade-off is sharply larger funding tail risk, borne by leveraged traders who keep positions across settlement.

Traders can verify the live cap and interval through GET /fapi/v1/fundingInfo?symbol=TACUSDT, inspect index constituents in Binance Futures, and compare mark, index and last price during a small test order. That check matters more than the announcement: Binance reserves the right to change index weights and contract parameters as conditions move.