What Is Front-Running?
Front-running is the practice of trading a security ahead of a pending order that is expected to move its price. The trader uses knowledge of the coming order, often a very large one, to buy or sell first and then profit when the price shifts in response. It is one of the most widely discussed forms of market manipulation because it exploits information that other market participants do not have.
How It Works
Large orders can move prices. When an institutional investor wants to buy a big block of shares, the buying pressure often pushes the price up as the order fills. Someone who knows this order is coming could buy shares beforehand, then sell them at the higher price once the order has lifted the market. The profit comes from the price movement caused by another trader's order, not from an independent view of the company.
The practice is most often associated with people who have access to order information because of their role, such as a broker handling a customer's market order or a limit order of significant size. Such a person has a duty to put the client's interests first, and trading for their own account first breaks that duty.
Why It Is Prohibited
In most regulated markets, front-running by brokers and other intermediaries is illegal or banned by exchange and industry rules. Regulators treat it as a breach of fiduciary duty or of the obligation to provide best execution to clients. Using confidential order information for personal gain can also overlap with insider trading rules, depending on the circumstances.
Why It Matters to Investors
Individual investors are rarely in a position to front-run, but understanding the practice helps explain why large orders are often split into smaller pieces and why brokers are held to strict conduct rules. Unusual trading activity ahead of major announcements or large transactions is the kind of pattern regulators monitor. Front-running is a reminder that markets depend on fair access to information and on intermediaries acting in their clients' interest.
Updated October 25, 2026. For general education only; not financial, tax or legal advice.