Spirit Aero was once part of Boeing. It was sold to private equity some 20 years ago and sold shares in an initial public offering in 2006 at $26. Over the years, Spirit added revenue from Airbus, which Spirit AeroSystems paid to take over facilities. That gives investors some indication of how tough things have been for Spirit AeroSystems lately.

Britain's competition regulator said on Friday it has cleared Boeing's planned acquisition of Spirit AeroSystems after deciding against an in-depth investigation into whether the deal would be anti-competitive.