Spoofing doesn’t depend on Rule 611. Manipulative intent is manipulative intent, regardless of the routing framework around it. But the tools, signals, and reference points that surveillance systems use to detect spoofing are deeply entangled with the market structure that Rule 611 created.

Prediction markets keep growing; trading hours are expanding; and firms are dealing with a lot more activity across a broader set of products and venues, often without oversight infrastructure to match.

For nearly two decades, Rule 611 has provided a common framework for navigating fragmented U.S. equity markets by requiring firms to avoid trading through protected quotations.