Time Priority

Time priority is a rule used in matching engines where, among orders at the same price level, the order that was placed first is executed first. This rule ensures that participants who provide liquidity earlier are rewarded for their contribution to the market.

When combined with price priority, it creates a structured and predictable environment for order matching. Time priority is critical for high-frequency traders who compete to be at the front of the queue at specific price points.

In fast-moving markets, even a few milliseconds can be the difference between getting an order filled or being bypassed. Exchanges must maintain precise time-stamping to enforce this rule correctly.

It prevents unfair manipulation and maintains confidence in the exchange infrastructure.