> ## 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.

# Order Matching Engine

> Learn how Roxom's matching engine processes orders during live trading and handles market-hours reopenings.

Roxom's matching engine continuously processes and executes orders based on their price, priority, and timing. Execution rules differ slightly between continuous (24/7) and explicitly designated market-hours contracts.

**Continuous Matching (24/7 Contracts):**
Contracts trading continuously (24/7) match orders in real-time without interruption. Incoming orders immediately match against the order book:

* **Buy orders** match against the lowest available asks.
* **Sell orders** match against the highest available bids.

Matching continues seamlessly around the clock until the incoming order fully executes or no further matches exist.

**Limited Matching During Closed Sessions (Market-hours contracts only):**
For contracts explicitly designated as market-hours only, matching behavior outside of designated hours is limited:

* **Limit orders** can still enter the book and immediately match against existing resting orders.
* **Market orders** cannot be placed and will be rejected outside trading hours.
* **Conditional orders** (stops, stop-limits, etc.) will not trigger outside market hours but remain pending activation at market open.

This structure allows liquidity-taking during off-hours without risking forced executions or triggering conditional orders at potentially unfavorable prices.

**Opening Sequence (Market-hours contracts only):**
Upon reopening after a closed session, Roxom immediately resumes trading:

1. The matching engine first checks the opening Mark Price and activates any **conditional orders** (stops, stop-limits, etc.) whose trigger conditions are met, placing them into the order book.
2. Immediately after conditional orders are activated, **continuous matching resumes** for all order types, including market orders.

There is **no opening auction**. Trading begins immediately, restoring full functionality.