“…With HFT now constituting a majority of transactions in major exchanges worldwide (SEC, 2014), those exchanges face competing incentives: they profit by accommodating HFT firms, yet still must retain traditional slower clients (O'Hara, 2015), many of whom feel that HFT puts them at a disadvantage. Some reform proposals intended to protect ordinary traders (e.g., by Budish et al (2015), Du and Zhu (2017), and Kyle and Lee 2017 The present paper contributes to the growing theoretical literature that addresses such questions. We develop an equilibrium model that spotlights the consequences of imposing a uniform delay on new orders while a class of previously submitted hidden liquidity-providing orders ("pegged" orders) are automatically repriced without delay.…”