Control of board composition determines subsidiary status, establishing holding-subsidiary relationships and rules for nominee and fiduciary share attribution. The section defines a subsidiary as a company controlled by another through board composition, predominant voting power or equity holding, or by transitive subsidiary relationships, and defines holding company as one whose subsidiary relationship exists. It specifies that board control includes appointment or removal powers and nominations, and sets attribution rules: fiduciary holdings are disregarded, nominee and subsidiary-held shares (subject to exceptions) are attributed to the parent, debenture-derived powers are excluded, and security holdings by lenders in ordinary course are not treated as parent-held. Foreign law subsidiary relationships are recognized domestically.