Why would a new exchange result in worse retail fills? They're obligated to get the NNBO price across all exchanges, and much of the retail flow doesn't even hit exchanges at all (internalized by Citadel/Virtu).

A monopoly is better for retail consumers?

I get that quants can get their alpha and whatever higher order terms, but if a consumer is buying to hold or using some other non-day trading strategy, why is this bad?

> A monopoly is better for retail consumers?

I'm confused why The New York Stock Exchange opening another NYSE office location has anything to do with monopoly status. The New York Stock Exchange is obviously still going to own both. If it was a monopoly before opening a second location it still will be, same as if it wasn't a monopoly.