Pablo Zuanic, a food and drink analyst for Susquehanna Financial Group, issued a report stating that a Trumpified White House would have a "meaningful and negative effect" on the brands. The Trump effect would affect both Mexicans living in the States -- which comprise a large portion of the brands' target bases -- and the overall appeal of Mexican-sourced beer.
While this seems like an abstract worry, the financial group (which literally gets paid to prognosticate on this stuff) clearly believes the backlash of Trump's potential immigration policies would screw over these Mexican brands so much that Constellation's stock would suffer greatly.
Lucky for them, Hillary Clinton is as likely to lose this election as an NFL kicker is to miss a 34-yard field goal. If you aren't a golfer, that's pretty much a sure bet. Laces out, kids. Stay thirsty.