The proposal would subject ATSs that effect transactions in listed stocks to significant new disclosure and transparency requirements.

On November 18, 2015, the US Securities and Exchange Commission (SEC) proposed rules (the ATS Transparency Proposal) to enhance operational transparency and regulatory oversight of alternative trading systems (ATSs) that trade stocks listed on a national securities exchange (NMS stocks).1 According to the SEC, because ATSs, including “dark pools,” have gained significant market share in NMS stocks and have evolved to more complex and sophisticated trading centers, the SEC believes that improving information transparency would enable market participants to better assess ATSs as potential trading venues.