I wrote a post on April 30th titled, MidCaps Set Up Short After Perfect Q1 Long. That set-up failed four weeks later, which is typical of my public plays. But the short set up again just a week after being stopped out, and triggered two weeks later below $272.62 (protective stop above $278.33). The minimum idiot wave move for MDY from here is $222.50 down to a "typical wave C" drop at $210 - $205. In a real crash-crash scenario, it could drop below $180.
I don't know anything about "Brexit," but I do understand that the dissolution of the EU would be a real mess and markets could be foretelling this with the projected down moves I've detailed above (and below on the chart).