The market quality implications of speed in cross-platform trading: evidence from Frankfurt-London microwave

Exploiting information transmission latency between stock exchanges in Frankfurt and London, and speed-inducing technological upgrades, we show that when cross-market latency arbitrage opportunities are linked to the arrival of information, high-frequency traders' (HFTs’) activities impair liquidity and enhance price discovery by facilitating the incorporation of public information into prices. Conversely, when cross-market latency arbitrage opportunities are driven by liquidity shocks, HFTs improve liquidity and reduce trading costs, thus incentivizing information acquisition and trading with private information. These findings underscore the complex nature of the association between trading speed and market quality and reconcile mixed evidence in the extant literature.