Best execution

Family VIII · Regulation

Not to be confused with market execution, order execution.

Best execution is a regulatory duty, not a promise of the best possible price on every trade. It requires firms to have execution policies, monitor venues and order-routing arrangements, and be able to demonstrate that client orders were handled in line with those policies. The specific rules, scope and reporting requirements vary by jurisdiction and regulator.

What the obligation covers

Best execution applies to firms that execute client orders or place them with other entities. The duty generally covers retail and professional clients, though the standard may differ by client category and jurisdiction. Firms must consider a range of execution factors, including:

Price and total cost
Speed and likelihood of execution
Likelihood of settlement
Order size and nature
Any other consideration relevant to the order

The relative importance of these factors depends on the client, the order and the market. A firm may prioritise speed over price for one order and price over speed for another, provided its policy explains how it does so.

Worked example: comparing venue outcomes

A firm routes a client buy order for 1,000 shares. Two venues are available. The firm compares the effective outcome after costs and likelihood of execution.

Venue comparison for a 1,000-share buy order

Venue A quoted price100.00100,000.00

Venue A commission0.05 per share50.00

Venue A total cost100,000.00 + 50.00100,050.00

Venue B quoted price100.02100,020.00

Venue B commission0.02 per share20.00

Venue B total cost100,020.00 + 20.00100,040.00

Lower total cost100,040.00 vs 100,050.00Venue B

Venue B has a higher quoted price but a lower total cost after commission. The firm must also consider whether Venue B can execute the full size at that price and within the client's time frame. If Venue B's likelihood of execution is materially lower, the firm may still choose Venue A, provided the decision is consistent with its execution policy and documented.

Policy, monitoring and evidence

Firms subject to best execution rules must maintain an order execution policy, disclose it to clients, and obtain client consent where required. They must monitor the effectiveness of their arrangements and review the policy regularly. Regulators may require firms to publish data on execution quality, including venue selection and order types. The exact reporting format, frequency and thresholds vary by jurisdiction and regulator.

Common misunderstandings

Best execution does not guarantee the best price available at any given moment. It is a process obligation: the firm must take sufficient steps, not achieve a specific outcome. It also does not apply to every transaction in the same way; for example, some jurisdictions exclude certain client categories or order types. Firms must be able to show why a particular execution decision was reasonable under their policy.

Often confused with

market execution: Market execution is a broker's order-handling model in which trades are filled at prevailing market prices without requotes, whereas best execution is a regulatory duty to seek the best overall result; the visible sign is that market execution describes a technical fill method, while best execution describes a legal standard of care.
order execution: Order execution is the general act of carrying out a client's buy or sell instruction, while best execution is the regulatory quality standard applied to that act; the visible sign is that order execution refers to the mechanical process, whereas best execution refers to the obligation to achieve the best possible result within that process.