The Spread Conflict
A market maker profits when the spread it captures on a trade is as wide as possible. A retail investor benefits when the spread is as narrow as possible. These interests are directly opposed. While market makers claim to provide 'price improvement' — execution at prices better than the NBBO — the degree of improvement they provide is constrained by their profit motive. The competitive discipline that would maximize price improvement is limited when order flow is captured through PFOF rather than competed for through execution quality.
The Information Conflict
A market maker that sees a large fraction of retail order flow before that flow reaches public markets possesses significant information about near-term supply and demand. Using this information to position the firm's own book before retail orders execute could disadvantage those orders — a concern that motivated FINRA's 2020 fine related to OTC order handling, where the regulator found that Citadel Securities had traded for its own account at prices that could have satisfied pending customer orders.
The Affiliated Hedge Fund Conflict
Citadel Securities and Citadel LLC (the hedge fund) are separate legal entities but share the same ultimate owner, Kenneth Griffin. Both entities operate under regulatory information barriers. However, the structural relationship — a market maker with the same owner as a hedge fund — creates potential conflicts that have drawn regulatory and Congressional attention, particularly in the context of the 2021 GameStop episode. No finding of actual coordination has been documented in public regulatory records.
Regulatory Responses to Conflicts
Regulators address market maker conflicts through a combination of rules (best execution, anti-front-running), surveillance (FINRA cross-market monitoring), information barriers (regulating the Citadel Securities/Citadel LLC relationship), and enforcement. Whether these tools are adequate to manage conflicts at the scale of Citadel Securities' market dominance is, in The Ethics Reporter's view, an open and important question.