Citadel Securities has urged the U.S. Securities and Exchange Commission to reconsider its proposal to eliminate a long-standing stock-trading regulation requiring trades to be executed at the best available displayed price. The dispute has become a significant market-structure issue, with potential implications for exchanges, market makers, brokers and investors as regulators reassess how U.S. equities should be traded.

Why the Trade-Through Rule Matters to U.S. Markets

The rule, adopted in 2005, is designed to prevent so-called trade-throughs, in which a stock transaction is executed at a price that is worse than a better displayed bid or offer available on another trading venue. Its purpose is to encourage brokers and trading firms to seek the best available prices across the fragmented U.S. equity market.

The SEC unanimously proposed eliminating the regulation in June, arguing that it has contributed to unnecessary costs and complexity and is no longer required in its current form. The proposal represents another major element of the regulator’s broader effort to reshape U.S. market structure.

Citadel Warns of Lower Liquidity and Weaker Price Discovery

Citadel Securities argues that removing the rule could produce unintended consequences. According to the firm, brokers could more easily bypass better displayed prices on public exchanges, increasing the incentive to route customer orders to alternative venues or internalize transactions rather than sending them to public markets.

Such a shift could affect the incentives for market participants to display competitive quotes. If less trading activity and fewer competitive prices are visible on exchanges, price discovery and overall market liquidity could weaken. Citadel also argues that retail investors could ultimately be affected if the changes reduce access to competitive execution prices.

The firm has also challenged the SEC’s economic analysis, arguing that the projected compliance savings of approximately $250,000 per trading day are modest relative to the scale of the U.S. equity market and do not adequately demonstrate that the benefits of eliminating the rule would outweigh the potential risks.

A Broader Debate Over the Future of Equity Trading

For Israeli investors following global capital markets, the debate is relevant because changes to U.S. market structure can influence liquidity, execution quality and the competitive dynamics between exchanges and alternative trading platforms. The issue is also increasingly connected to the emergence of new trading technologies, including platforms offering tokenized equities.

Citadel has proposed a less disruptive alternative: establishing a minimum trading-volume threshold for exchanges to qualify for protected-quote status. The approach would preserve elements of the existing framework while potentially reducing some of the regulatory burden that the SEC has identified.

The SEC’s next steps will therefore be closely watched by exchanges, market makers, brokers and institutional investors. The central question is whether regulators will proceed with a broad repeal or modify the proposal to address concerns over liquidity and investor protection. Any final rule could have lasting implications for how orders are routed, how prices are discovered and how competition develops across U.S. equity markets.