Is the drop of -$0.06 due to the Boeing-Embraer JV?
I have serious doubts that the deal between Boeing and Embraer is the main reason for the current drop of the SP: Here is my reasoning:
As Bellemare said, they currently only have a vague idea of the final deal. I guess the document is mostly an agreement to negociate a final deal;
There are mid-term elections this year in the US and this might not be approved;
Trump might be very unhappy with Boeing as it is obvious Boeing would eventually get much work done by Embraer resulting in a net loss of work done in the US. See what is currently happening with Harley-Davidson;
Assuming everything goes as planed the final deal is in 18 months from now giving Bombardier and Airbus a huge head start on the competition:
They would need a final approbal of the Brazil Government;
The bottom line is that the CSeries is a much better plane than whatever Embraer has in stock.
Now that the big fishs ate all of the small frys with their poorly managed stop loss orders, it is time for the SP to turn around and climb back into the green.