Citadel Securities is courting sovereign wealth funds, asset managers, insurers, and large banks in Asia to participate in its around-the-clock U.S. equity trading service.

Based in Miami, the firm began offering 24/7 U.S. stock trading in November of last year and is seeking to bring more non-U.S. institutional clients into extended-hours trading, a segment still led by retail activity.

The move comes as major U.S. exchanges contemplate longer trading windows, reflecting a broader shift toward continuous markets.

The New York Stock Exchange is evaluating a plan to allow some trading for about 23 hours a day, five days a week beginning in December, while Nasdaq has signaled a similar 23-hour weekday schedule.

Joseph Mecane, Citadel Securities' head of execution services, said the firm would connect to those venues once they operate 23 hours a day, five days a week, and the necessary infrastructure is in place, while continuing to provide trading as a single counterparty.

The company has been hiring to support growth in round-the-clock trading. Sina Finance reported that Citadel Securities has about 10 employees in Hong Kong handling sales and client service, and roughly 50 in the United States.

Mecane added that about 11% of U.S. stock trading volume occurs in premarket and after-hours sessions, and that Citadel Securities accounts for at least half of U.S. retail trading in the overnight window.