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

# USDT-BTC

> Specific details for the USDT-BTC perpetual futures contract.

| **Contract Code**           | `USDT-BTC`                                                                                                                                                                                                                                                                                                                 |
| --------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Underlying Index Price**  | • **Stablecoin leg:** **USDT/USD** spot price from Binance / Pyth <br />• **BTC Price:** 3-venue 4-hour VWAP spot composite of Binance (BTC/USDT); Pyth (BTC/USD); Coinbase (BTC/USD).                                                                                                                                     |
| **Contract Size**           | Notional of **1,000 USDT**, quoted & settled in BTC                                                                                                                                                                                                                                                                        |
| **Quote / P\&L Currency**   | BTC                                                                                                                                                                                                                                                                                                                        |
| **Tick Size**               | 0.000001                                                                                                                                                                                                                                                                                                                   |
| **Trading Hours**           | **24 / 7 continuous order book.**                                                                                                                                                                                                                                                                                          |
| **Mark-Price Construction** | \*\*Mark Price = median(P¹, P², P³), Where: \*\*<br />**Price 1 (P¹)** = Index Price × 1+LastFundingRate×(TimeUntilFunding/8) <br />**Price 2 (P²)** = Index Price plus a rolling **2.5-minute average basis**, where the basis is defined as *(Bid1 + Ask1)/2 − Index Price*. <br />**Price 3 (P³)** = Last traded price. |
| **Funding Snapshots**       | 00:00 UTC • 08:00 UTC • 16:00 UTC (every 8 h)                                                                                                                                                                                                                                                                              |
| **Funding-Rate Formula**    | **Premium Index + Interest Rate**; Interest Rate = 0.03% / day (0.01% / 8 h). Caps ± 3 % per 8 h.                                                                                                                                                                                                                          |
| **Leverage & Margin**       | Max Leverage 10x; Maintenance margin 25% of Initial Margin.                                                                                                                                                                                                                                                                |
| **Liquidation Logic**       | • Trigger when Equity \< MM. <br />• For long positions = Entry Price × (1−Initial Margin Rate + Maintenance Margin Rate) <br />• For short positions = Entry Price × (1 + Initial Margin Rate - Maintenance Margin Rate)                                                                                                  |
| **Order Types / TIF**       | Limit, Market, GTC, GTD, IOC.                                                                                                                                                                                                                                                                                              |
| **Min / Max Order Sizes**   | **Market Max:** 0.5 BTC <br />**Limit Max:** 0.5 BTC                                                                                                                                                                                                                                                                       |