The company that inspired Michael Lewis’s Flash Boys just won another round against one of Wall Street’s most powerful trading firms. A federal appeals court has rejected Citadel Securities’ challenge to IEX’s new options exchange, clearing the way for a launch that could reshape how options are traded in the US.
The US Court of Appeals for the Eleventh Circuit ruled on May 29 against Citadel Securities, upholding the SEC’s approval of IEX Options. That approval had been granted on September 18, 2025, but Citadel filed a petition with the court just a month later, on October 17, effectively putting IEX’s plans in legal limbo.
That limbo is now over. IEX Group is targeting an October 2, 2026 launch date for the new exchange.
The 350-microsecond fight
At the heart of this legal battle is something called the Options Risk Parameter, or ORP. It’s a hardware-based feature that introduces a 350-microsecond delay into the trading process. To put that in perspective, 350 microseconds is about one-third of a millisecond. A blink of an eye takes roughly 300,000 microseconds.
