Open-market manipulation

Open-market manipulation is manipulation carried out through transactions that are, individually, entirely ordinary and lawful. Courts have divided on whether trades that are facially legitimate can be manipulative purely by reason of intent, and the doctrinal question remains unsettled.

history and doctrine · updated 2026-10-16

Where does open-market manipulation come up?

This term is used in the following manipulation techniques, each explained in full on its own page.

• Marking the close — Marking the close is trading in the final minutes of a session specifically to move the closing price, which is the price that sets portfolio valuations, margin calls, index levels and derivative settlements.
• Momentum ignition — Momentum ignition is entering a burst of aggressive orders designed to trigger other participants' momentum strategies, creating a price move the initiator then trades against.

Enforcement actions involving these techniques

See also

• Scienter — Scienter is the mental state of intending to deceive, manipulate or defraud. It is a required element of a Rule 10b-5 claim, and i…
• Artificial price — An artificial price is one that does not reflect the genuine forces of supply and demand. Proving artificiality is a required elem…

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