Citadel Securities plans to buy the market-making unit of smaller rival IMC Financial Markets, expanding its presence at the New York Stock Exchange.
The deal would shore up Citadel Securities' position as the largest floor broker on the exchange, according to a statement. Terms weren't disclosed.
Citadel Securities, which oversees daily trading in more than 1,500 NYSE-listed securities, is among the designated market makers responsible for ensuring that trading runs smoothly from the floor of the exchange.
Amsterdam-based IMC runs the third-biggest designated market maker at the NYSE and oversaw trading in 18% of stocks listed on the exchange earlier this year, while Citadel Securities handled 44%, according to published reports.
Citadel Securities also handles more than 40% of retail equity trading volume in the U.S., according to the company.
Once run by Wall Street banks, the floor broker posts on the Big Board have been taken over by high-speed trading firms in recent years. Citadel Securities purchased its designated market-maker business in 2016.
Though the U.S. stock market is almost entirely electronic, NYSE touts its floor brokers as a key ingredient in keeping trading orderly and less volatile.
"We are thrilled to further extend our presence at the New York Stock Exchange," Joe Mecane, head of execution services for Citadel Securities, said in the statement.
IMC, founded in 1989, has more than 800 employees, according to its website.