Perpetual Contract Funding Fee & Delivery Contract Settlement Rules – XCoin Service

1. Perpetual Contract Funding Fee

Since perpetual contracts have no expiration and delivery date, a funding fee mechanism is required to anchor the contract price to the spot price.

1.1 Core Formula

Funding Rate = clamp[Average Premium Index + clamp(Combined Interest Rate – Average Premium Index, 0.05%, -0.05%), Premium Deviation Upper Limit, Premium Deviation Lower Limit]

1.2 Key Components & Calculations

1.2.1 Combined Interest Rate

Combined Interest Rate = 0.03% / (24 / Settlement Cycle)

Example: For the BTCUSDT perpetual contract, the settlement cycle is once every 8 hours.Combined Interest Rate = 0.03% / (24 / 8) = 0.01%

1.2.2 Premium Deviation

Premium deviation is classified based on the maximum leverage of the contract (≥ 30x or < 30x).

Indicator	USDT-Margined Contracts with Max Leverage ≥ 30x	USDT-Margined Contracts with Max Leverage < 30x
Premium Deviation Lower Limit	-0.75 × Maintenance Margin Ratio	-3%
Premium Deviation Upper Limit	0.75 × Maintenance Margin Ratio	3%

Note: If the maximum leverage of the contract is reduced to 25x or lower, the funding rate upper limit of ±3% will be automatically applied.

1.2.3 Premium Index

Premium Index = [Max(0, Buy Impact Price – Index Price) – Max(0, Index Price – Sell Impact Price)] / Index Price

Buy Impact Price: The average transaction price when executing trades worth the "Impact Margin Amount" at the buyer’s quoted price.
Sell Impact Price: The average transaction price when executing trades worth the "Impact Margin Amount" at the seller’s quoted price.
Impact Margin Amount: 200 USDT / Initial Margin Ratio of the Highest Leverage Tier

1.2.4 Average Premium Index

Calculated using a weighted average algorithm, which incorporates premium indices from the end of the previous settlement cycle to the current time.

Example:The average premium index at time Tn = (1 × Premium Index at T1 + 2 × Premium Index at T2 + ... + n × Premium Index at Tn) / (1 + 2 + ... + n).For a contract with funding fee collection every 8 hours, the funding rate calculated at 14:59 (UTC+8) uses premium indices recorded every 5 seconds from 07:00 to 14:59 (UTC+8), where n = 5760 (total 5-second intervals in 8 hours).

1.3 Calculation & Settlement Cycles

Item	Rule
Calculation Cycle	Calculated once per minute; the latest funding rate is used for fee collection/payment.Example: For funding fee settlement at 16:00 (UTC+8), the rate calculated at 15:59 (UTC+8) is applied.
Settlement Cycle	8 hours per cycle, occurring daily at 08:00 (UTC+8), 16:00 (UTC+8), and 24:00 (UTC+8).
Settlement Principle	Users only need to pay or receive funding fees if they hold an open position at the settlement time. No fees are incurred if the position is closed before fee collection.
Settlement Currency	USDT

2. Delivery Contract Settlement Mechanism

2.1 Delivery Time

The contract automatically enters the delivery process on the specified expiration date and time (usually 16:00 UTC+8).

2.2 Delivery Method

Settled at the delivery price, where:Delivery Price = Average of the index price in the 30 minutes before expiration (see Index & Pricing Mechanism below for details).

2.3 Delivery Fee

Delivery Fee = ABS(Number of Contract Contracts) × Contract Face Value × Delivery Price × Delivery Fee Rate

No handling fee is charged for position delivery.

2.4 Settlement Currency

USDT

3. Early Settlement Mechanism for Delivery Contracts

Under necessary circumstances, delivery contracts may undergo early delivery. The specific delivery time shall be subject to the announced settlement time.

Settlement Price = Average of the index price in the 30 minutes before the (early) settlement time.

4. Contract Trading Rules

The platform imposes restrictions on the minimum order quantity and minimum price fluctuation for user transactions. Below is an example of contract trading rules.To view the full list of comparative trading rules, please refer to Trading Guide - Viewing Derivatives Trading Rules。

4.1 Example: BTC Perpetual Contract & ETH Perpetual Contract

Indicator	USDT-Margined Contracts with Max Leverage ≥ 30x	USDT-Margined Contracts with Max Leverage < 30x
Premium Deviation Lower Limit	-0.75 × Maintenance Margin Ratio	-3%
Premium Deviation Upper Limit	0.75 × Maintenance Margin Ratio	3%

4.2 Position Limit Mechanism

Position limits are set for contract trading to control risks and prevent users from holding an excessively high proportion of total market positions.

4.2.1 Tiered Position Limits (by Risk Tier)

If your risk quota exceeds the maximum tier limit, you cannot open new positions.
If your risk quota exceeds the maximum tier, the margin used (initial and maintenance) will be calculated based on the maximum tier.

Note: Tiered position limits only apply to cross-currency cross-margin mode. No tiered position limits apply to portfolio margin mode.

4.2.2 Total Position Quantity Limit

When your position quantity on the platform exceeds a certain threshold, the platform will restrict your position quantity based on the position limit ratio:

If (Your Current Position Quantity + Pending Orders in the Same Direction as Your Position) / Total Platform Positions ≥ Position Limit Ratio → You cannot open new positions.
For master-sub accounts: If (Total Position Quantity of Master-Sub Accounts + Pending Orders in the Same Direction) / Total Platform Positions ≥ Position Limit Ratio → The master-sub account group cannot open new positions.

Appendix: Index & Pricing Mechanism

The delivery price is determined by the average index price in the 30 minutes before contract expiration. The index price is typically calculated based on real-time spot prices from multiple mainstream exchanges (to avoid price manipulation) and weighted by trading volume or other factors (specific calculation logic is subject to platform announcements).