Example. Corporation P owns directly 50 of the 100 shares of the only class of stock of corporation S. A, an officer of P, owns directly 30 shares of S stock which P has an option to acquire. If, under paragraph (b)(4) of this section, the 30 shares owned directly by A are treated as not outstanding, P would be treated as owning stock possessing only 71 percent (50/70) of the total voting power and value of S stock, and S should not be a member of a parent-subsidiary group of trades or businesses under common control. However, because the 30 shares owned by A that P has an option to purchase are considered as owned by P under paragraph (b)(2) of this section, and that ownership plus P's direct ownership of 50 shares result in S's membership in a parent-subsidiary group of trades or businesses under common control for 1985, the provisions of this paragraph apply. Therefore, A's stock is not treated as an excluded interest and S is a member of a parent-subsidiary group consisting of P and S.
26 C.F.R. §1.414(c)-3