Glossary · Trading and execution
Best execution is an adviser's obligation to seek the most favourable terms reasonably available for a client's transaction — an obligation about process, not about any single trade's outcome.
A firm can obtain an excellent price on every trade and still fail the obligation, because what is examined is whether the firm periodically and systematically evaluated its execution arrangements and can show it.
Price is one factor. Speed, likelihood of execution and settlement, order size, and the character of the market all count. A firm that reviews only price has reviewed one input.