Alaska Air announced Friday it has grounded its fleet of 65 Boeing 737 MAX-9 jets after a plane lost a section of its fuselage midair. The Friday night incident should generate a market response on Monday when Boeing stock opens for trading, considering investors’ long, complicated history with the MAX. Flight 1282 took off from Portland, Ore., at about 8 p.m. on Jan. 5, lost a window, and was able to return safely to the Portland airport, the airline said. “My heart goes out to those who were on this flight,” said Alaska CEO Ben Minicucci in a news release. “I am so sorry for what you experienced. I am so grateful for the response of our pilots and flight attendants. We have teams on the ground in Portland assisting passengers and are working to support guests who are traveling in the days ahead.” Alaska is working with Boeing and