High-frequency trading (HFT) has staged a stunning revival, with firms like Jane Street and Citadel Securities generating over $50 billion in net trading revenue in 2025 alone. Once deemed obsolete after intense competition eroded spreads and profits, HFT now thrives amid consolidation and diversification. Michael Lewis’s *Flash Boys* once painted HFT as a fading relic, but today’s landscape is dominated by firms expanding into crypto, fixed income, and arbitrage across stocks, options, and ETFs.

The sector’s resurgence stems from post-2017 consolidation—mergers like Virtu’s acquisition of KCG and Two Sigma’s purchase of Timber Hill—reducing competition. Larger firms leverage scale to absorb tech and data costs, while retail trading’s surge post-COVID flooded markets with volatility. As Jefferies noted, retail activity now surpasses mutual funds, hedge funds, and banks combined, fueling HFT’s profitability through widened spreads.

Modern HFT firms increasingly resemble statistical arbitrage funds, holding positions for days or weeks. Jane Street’s success hinges on mark-to-market gains from long-term bets on tech firms like Anthropic, contrasting with rivals relying on personal investments (e.g., Susquehanna’s Jeff Yass in TikTok). This evolution reflects HFT’s shift from nanosecond stock trades to multi-dimensional market-making.

Despite lingering skepticism, HFT’s dominance in speed and volume remains unchallenged. Even Lewis’s critiques ring hollow as the industry adapts to turbulent markets and regulatory shifts. The era of co-location arms races may be over, but HFT’s core—exploiting microsecond advantages—endures, now bolstered by crypto’s chaotic liquidity and retail frenzy.