In early 2021, the usually relatively obscure topic of US equities market structure hit mainstream news headlines. In March, an investing subreddit called r/wallstreetbets triggered a short squeeze in brick-and-mortar video games retailer GameStop’s stock, making it the most highly traded asset in the US. The ensuing “meme stock” frenzy was framed as nothing less than all-out class war, and saw possible conflicts of interest in the practice of payment for order flow wind up on the agenda of the