By Luc Olinga The legacy carmaker is one of Rivian’s two major shareholders. The other main shareholder is Amazon. It’s official. Ford (F) – Get Ford Motor Company Report disclosed in a Securities and Exchange Commission document that it sold Rivian (RIVN) – Get Rivian Automotive, Inc. Class A Report stock. This decision represents a blow to the upstart manufacturer of electric vehicles, which is trying to convince investors it can manage increases in production rates while experiencing disruptions in supply chains. Ford, which held 102 million Rivian shares, sold 8 million of those Rivian sha…