High-frequency trading algorithms should face regulatory limits on transaction speed to prevent market flash crashes.

This was a closely contested debate in which both sides demonstrated substantive knowledge of market microstructure and HFT regulation, but neither side delivered a truly decisive blow. The debate largely revolved around three axes: the empirical record of flash crashes, the liquidity and efficiency benefits of HFT, and the comparative merits of speed limits versus targeted circuit breakers.

Pro built their case around the systemic risk narrative, anchoring heavily on the May 6, 2010 Flash Crash and supplementing with references to the 2012 Knight Capital incident, the 2015 Treasury Flash Rally, and international regulatory experiments like IEX's speed bump. Pro's strongest moments came when highlighting the "phantom liquidity" problem—the documented tendency of HFT firms to withdraw liquidity precisely during periods of market stress, when it is most needed. This effectively challenged Con's central claim that HFT reliably provides liquidity benefits.

Con countered by emphasizing the staleness of Pro's primary evidence (a 16-year-old event), the substantial regulatory reforms implemented since 2010 (Reg SCI, LULD bands, consolidated audit trail), and the robust academic literature showing HFT tightens bid-ask spreads and improves price discovery under normal conditions. Con's most effective move was identifying Pro's internal contradiction: acknowledging that HFT didn't cause the initial 2010 downturn while still advocating speed limits as the primary remedy.

The debate's turning point came in Round 3, where Con more effectively pressed the argument that post-2010 regulatory evolution had already addressed many of Pro's concerns, while Pro struggled to explain why existing circuit breakers were insufficient beyond asserting they were "reactive." Pro's closing argument in Round 4 was notably weaker, becoming somewhat repetitive and failing to introduce fresh evidence or adequately rebut Con's point about the IEX speed bump being a voluntary market mechanism rather than a regulatory mandate.

Both sides suffered from some cherry-picking and occasional overstatement, but Con maintained slightly better logical consistency throughout and more effectively engaged with Pro's specific claims.