5.13.3. Regulation ATS
Regulation ATS requires every alternative trading system to register with the SEC and FINRA as broker-dealers. No ATS may use the word “exchange” or “stock market” in its name, but if an ATS achieves dominance in the market, the SEC may require it to become an exchange.
If an ATS trades more than 5% of the trading volume of an exchange-listed stock and it displays subscriber orders to any person (other than ATS employees), the ATS must publicly display its best bid-and-ask prices for that stock on an exchange. It must also allow any broker-dealer having access to those quotes to complete