Who this is for — Readers who entrust an order to an intermediary and want to distinguish the regulatory obligation, routing policy and measured quality of the fill.
Best execution requires certain intermediaries to seek the most favourable execution terms for the client under the applicable framework. It is not a promise that, viewed with hindsight, every order will receive the best price that appeared on any market. The obligation covers multiple factors, organisational arrangements, venue selection, monitoring and the ability to demonstrate how an order was handled.
In plain language — The intermediary must organise itself and act to obtain the best result contemplated by the rules and the order's characteristics. It cannot control every market movement or guarantee a perfect counterfactual.
The MiFID II framework
Article 27 MiFID II requires investment firms to take all sufficient steps to obtain the best possible result when executing orders. The stated factors include:
- price;
- costs;
- speed;
- likelihood of execution;
- likelihood of settlement;
- size and nature of the order;
- any other relevant consideration.
For a retail client, Article 27 determines the best result in terms of total consideration: the price of the instrument plus costs directly related to execution, including venue, clearing and settlement fees and other payments to third parties involved. This does not make speed or likelihood of a fill irrelevant: those factors can affect whether that result can be obtained.
A specific client instruction must be followed for the aspects it governs. If the client imposes a venue, limit price or other condition, the intermediary's decision-making scope is reduced; the outcome must therefore be assessed in light of that instruction, not against a different order imagined after the fact.
Execution policy and control
Best execution is not confined to the submission click. MiFID II requires an order execution policy describing, for each class of instruments, the venues and selection factors. The firm must give the client comprehensible information about the policy, obtain the required consent, disclose when the policy contemplates execution outside a trading venue and obtain the express consent required for that possibility.
The arrangements and included venues must be monitored regularly. The firm must correct deficiencies, communicate material changes and be able, on request, to demonstrate that it executed the order in accordance with its policy. Using a single venue is not automatically incompatible with best execution, but the intermediary must be able to demonstrate that the choice allows it to obtain better results on a consistent basis and must consider changes in the market.
Best price, best result and fill quality
| Concept | Question it answers |
|---|---|
| Best visible price | Which quote was published within a given perimeter and at a given moment? |
| Best execution | Did the intermediary meet the applicable obligation through an adequate policy, process and controls? |
| Execution quality | What measurable results did orders and venues produce against stated benchmarks? |
Price is central, but a quote unavailable for the requested quantity, a very low likelihood of a fill or uncertain settlement can change the assessment. Likewise, fast execution is not necessarily better if it entails a higher avoidable total cost.
In the United States, the SEC describes a broker's duty as seeking the most favourable terms reasonably available under the circumstances. It considers, among other factors, opportunities for price improvement, speed and likelihood of execution. The SEC also states that execution-quality statistics do not by themselves determine whether the duty was met: the assessment depends on the facts and circumstances. The US framework and MiFID II must not be presented as identical rules.
Why the result is not guaranteed
Between decision and fill, quotes and quantities may change; liquidity may be fragmented or hidden; an order may receive partial fills or remain unexecuted. An intermediary may comply with its process without obtaining the theoretically best price observable with hindsight. Conversely, one favourable fill does not show that routing, conflicts and controls are adequate over time.
Analysing an order requires at least its instructions, type, quantity, timestamps, venue, individual fills, costs and comparable quotes. Execution-quality indicators and transaction costs are useful evidence, not automatic substitutes for regulatory analysis.
Boundary — “Best execution” does not mean “best price guaranteed”, nor does it permit costs, likelihood of execution, settlement, size, the nature of the order or client instructions to be ignored.
Sources
- European Securities and Markets Authority, MiFID II, Article 27 — Obligation to execute orders on terms most favourable to the client — factors, retail total consideration, policy, monitoring and demonstrability.
- European Securities and Markets Authority, Q&A 1016 — Best execution: “all sufficient steps” — level of the obligation and results sought on a consistent basis.
- U.S. Securities and Exchange Commission, Best Execution — broker duty and assessment factors in the United States.
- U.S. Securities and Exchange Commission, Disclosure of Order Execution and Routing Practices — facts-and-circumstances assessment and the limits of execution statistics alone.