On May 6th, the Stock market crashed and rebounded all in about one hour. In this period some stocks lost half their value or more, then regained this value. A very strange day. I am not sure if it suggests that market microstructure (meaning how markets are made, orders submitted and cleared, and so forth) is critical (the crash) or irrelevant (the rebound). Anyway, we now have two things to think about.
First, the CTFT and SEC have issued the preliminary findings of their investigation of this event. Link here.
Second, we now have circuit breakers that operate across exchanges. I am not sure why we have circuit breakers, but if we have them, it surely seems better to have the be universal rather than exchange-specific.