Although best execution can be measured ex post over time, it cannot be measured for a single trade. Best execution cannot be judged independently of the investment decision. Best execution cannot be known with certainty ex ante, it depends on the particular circumstances of the trade. Each party to a trade determines what best execution is.

Best execution cannot be judged independently of the investment decision. Prudence and best execution both attempt to improve portfolio performance and meet fiduciary responsibilities. Best execution cannot be known with certainty ex ante. Relationships and practices are integral to best execution.

Some strategies might have high trading costs but that does not mean they should not be pursued if in net they enhance portfolio value. Best execution depends on the circumstances of the trade. Best execution can be measured after the fact for a series of trades.