Reg NMS
MarketsDefinition
Regulation National Market System (2005). Set rules for US equity markets including the trade-through rule (orders must execute at NBBO), Order Protection Rule, sub-penny rules, and Rule 605/606 execution-quality disclosures.
Helped fragment US markets into 16 exchanges + dozens of dark pools — competition lowered fees but increased complexity. Reg NMS reform has been periodically debated; recent SEC proposals didn't fully advance.
Helped fragment US markets into 16 exchanges + dozens of dark pools — competition lowered fees but increased complexity. Reg NMS reform has been periodically debated; recent SEC proposals didn't fully advance.