What HFT Means in Practice
High-frequency trading involves executing orders in microseconds or nanoseconds using algorithmic strategies that exploit tiny price discrepancies and information advantages. Citadel Securities' HFT operations allow it to process and respond to market data faster than any retail investor can observe, quote, or act. This speed advantage is the foundation of Citadel's ability to make markets profitably — and it is necessarily subsidized by less-fast market participants, including retail investors.
The Information Advantage
Citadel Securities receives retail order flow before that flow reaches exchanges. This 'first look' at incoming orders provides market intelligence about short-term directional pressure in individual stocks. While information barriers are supposed to prevent this from being traded on, the aggregate market-making decisions Citadel makes are necessarily informed by the order flow it processes — creating an informational asymmetry with retail investors.
The IEX Challenge
IEX (Investors Exchange) was founded specifically to address HFT advantages, using a 350-microsecond 'speed bump' to level the playing field between HFT firms and other investors. Citadel Securities and other HFT firms have opposed IEX's expansion and regulatory recognition. The firm's lobbying against IEX's exchange application documented Citadel's commercial interest in preserving HFT advantages over retail investors.