Citadel Securities is pushing back against the SEC's plan to eliminate a foundational stock-trading rule. In a comment letter submitted on August 17, 2026, the firm argued that rescinding Rule 611 of Regulation NMS could reduce liquidity, weaken price discovery, and leave retail investors worse off. The SEC proposed eliminating the rule, which prevents brokers from executing trades at prices worse than the best available price displayed on another exchange, on June 11, 2026.
Market Impact
The firm's central concern is that without the rule, brokers could increasingly choose to fill orders internally, rather than on public exchanges. This could lead to less reliable price signals and divert order flow away from public exchanges. Citadel Securities warned that the proposal could concentrate more trading in private venues with limited transparency.
Alternative Proposal
Instead of eliminating the rule, Citadel Securities suggested implementing a minimum volume threshold for exchanges to receive 'protected quote' status. This would address issues with small, low-volume exchanges that display competitive prices but lack liquidity to fill orders at those prices.