The company behind Michael Lewis's Flash Boys has won another legal battle against Citadel Securities. A federal appeals court rejected Citadel's challenge to IEX's proposed 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 against Citadel Securities on May 29, upholding the SEC's approval of IEX Options. That approval was granted in September 2025, but Citadel's legal challenge had kept IEX's plans in limbo. With that ruling, IEX is now targeting an October 2, 2026 launch date.
The 350-Microsecond Delay
At the core of the dispute is IEX's Options Risk Parameter (ORP), a hardware feature that introduces a 350-microsecond delay into the trading process. That's roughly one-third of a millisecond-an almost imperceptible pause designed to protect liquidity providers from faster traders exploiting latency arbitrage.
IEX has fought this fight before. Its equities platform won approval for a similar speed bump in 2022. Citadel challenged that too-and lost that too. Citadel Securities, led by Ken Griffin, argued the delay mechanisms are anticompetitive. The court disagreed, for the second time.
Why IEX Options Matters
IEX Options prioritizes customer orders and uses a pro-rata allocation model, filling orders proportionally rather than rewarding the fastest connections. Founder Brad Katsuyama became a household name after Lewis's 2014 book exposed how high-frequency traders were front-running ordinary investors. IEX initially announced plans for the options venue in 2024, targeting Q1 2026. The Citadel lawsuit delayed that by only a few months.