Order Protection Rule - Rule 611 of Regulation NMS

Rule 611, adopted June 9, 2005, effective August 29, 2005 (see 70 FR 37495), requires a trading center (which included national securities exchanges, national securities association, alternative trading systems, exchange market makers, OTC market makers) to establish, maintain, and enforce written policies and procedures that area reasonably designed to prevent trade-throughs of protected quotations and, if relying on an exception, that are reasonably designed to ensure compliance with the terms of the exception.

The latest form for Order Protection Rule - Rule 611 of Regulation NMS expires 2023-10-31 and can be found here.