Trading ahead of large orders, also known as "front-running," is a manipulative practice where a trader executes trades before a large order is filled, taking advantage of the anticipated market impact. This can:

1. _Disadvantage the large order_: Affecting the price at which the order is filled.

2. _Manipulate market prices_: Influencing prices by trading ahead of the large order.

3. _Undermine market fairness_: Unfairly profiting from insider knowledge of the large order.

Front-running can occur in various forms, including:

1. _Trading on non-public information_: Using knowledge of the large order before it is publicly disclosed.

2. _Using advanced algorithms_: Executing trades rapidly, ahead of the large order.

3. _Colluding with others_: Working with others to trade ahead of the large order.

To prevent and detect front-running, regulators and exchanges use:

1. _Trade surveillance_: Monitoring trading activity for suspicious patterns.

2. _Order book analysis_: Reviewing order book data to identify potential front-running.

3. _Market monitoring_: Analyzing market data for unusual activity.

4. _Regulatory enforcement_: Imposing penalties and fines for engaging in front-running.

5. _Market participant education_: Promoting fair market practices and awareness of manipulative tactics.

By addressing front-running, regulators aim to maintain a fair, transparent, and orderly market environment.