The addition of these ATD assets is the latest step in the expansion of Citadel Securities. This transaction will further enhance Citadel Securities' position as an industry leader, help the firm provide retail investors with access to additional liquidity and offer strong execution quality to more clients.

"This acquisition supports the growth of our industry-leading equities business and reflects our commitment to leveraging our global footprint, cutting-edge technology and trading expertise to meet the diverse needs of our clients as traditional providers continue to exit this space," said Jamil Nazarali, Head of Citadel Execution Services.

The acquisition follows the recent announcement of Citadel Securities' purchase of KCG Holding's Designated Market Maker business at the New York Stock Exchange.

Citadel Securities is the leading retail equities market maker, executing approximately 14%1 of U.S. consolidated volume in listed equities and 34%2 of U.S. retail equities volume as well as approximately 21%3 of U.S.-listed equity options volume.

Established in 2002, Citadel Securities has a long track record of transforming markets through solutions that reduce trading costs, increase transparency, and improve execution quality for all investors.

Citadel Securities has partnered with ATD and Citi to transition clients to its platform.