From Traderpedia

Spoofing is a futures trading tactic involving posting huge lot orders at the immediate bid or ask in order to trick locals or other traders into a position leaning against the oder volume, and then flipping the order to the other side or pulling it altogether.

Support or resistance areas can also be faked in a similar fashion, by posting size into the order book near the current market, and then pulling the order when that price starts to trade.

Spoofing is almost universally condemned as unfair, or market manipulation by those traders adversely affected by it.

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