Interlocking ownership, may take the form of reciprocal exchange of stock between large concerns, private stockholdings which establish a community of control among nominally independent enterprises, jointly owned subsidiaries, or the monopolization of an industry’s international trade by a combination of concerns governed by a single holding company. Ordinary restrictive agreement among businessmen, takes the forms from a simple contract to fix prices or allocate sales to an international trade association which maintains an incorporated joint sales agency for its members.