Regulation ATS And Dark Pool Disclosure

An alternative trading system (ATS) — commonly called a dark pool — is a trading venue that matches buyers and sellers without publicly displaying orders before execution, unlike a lit exchange. Regulation ATS, adopted in 1998 and significantly strengthened in 2018, requires these venues to register with the SEC and, since the 2018 amendments, to file a public disclosure document called Form ATS-N describing exactly how the venue operates.

Form ATS-N forces disclosure of details users previously had to take on faith: whether the operator or its affiliates trade against client orders on the same venue, how orders are prioritized and matched, what order types exist, and what data the operator or its affiliates can see about incoming flow. This mattered because dark pools had faced multiple enforcement actions for undisclosed practices — operators quietly favoring certain participants, or letting proprietary trading desks see order flow information other users could not.

Because dark pool trades still aren't pre-trade transparent, the price-discovery role stays with lit exchanges; a dark pool relies on the lit market's quotes as its reference price and typically executes at or inside the prevailing National Best Bid and Offer, which is exactly why regulators focus disclosure requirements on venue mechanics rather than pre-trade prices.