In choosing a particular regulatory regime it is important to remember that no system will fully eliminate inappropriate or illegal activities. Banking examiners, for example, find it difficult to unearth fraud and embezzlement in their early stages. Securities regulators have difficulty ferreting out malfeasance. Even trading on exchanges does not in itself eliminate all endeavors at manipulation, as the Hunt brothers' 1979-80 fiasco in silver demonstrated. The primary source of regulatory effectiveness has always been private traders being knowledgeable of their counterparties.
Government regulation can only act as a backup.
It should be careful to create net benefits to markets.