paragraph (2), during the 4-year period ending on the acquisition date, such acquisition shall be treated as pursuant to a plan. (6) Certain transfers disregarded The transfer of properties or liabilities (including by contribution or distribution) shall be disregarded if such transfers are part of a plan a principal purpose of which is to avoid the purposes of this section. (7) Special rule for related partnerships For purposes of applying paragraph (1)(C)(i) to the acquisition of a trade or business of a partnership, except as provided in regulations, all partnerships which are under common control (within the meaning of section 482) shall be treated as 1 partnership. (8) Regulations The Secretary shall prescribe such regulations as may be appropriate to determine whether any transaction or series of transactions is a corporate inversion or corporate expatriation, including regulations— (A) to treat warrants, options, contracts to acquire stock, convertible debt interests, and other similar interests as stock, and (B) to treat stock as not stock. (d) Other definitions For purposes of this section— (1) Accumulated deferred foreign income (A) In general The term accumulated deferred foreign income means the excess of— (i) the undistributed earnings of the controlled foreign corporation, over (ii) the undistributed U.S. earnings of such controlled foreign corporation. (B) Undistributed earnings The term undistributed earnings means the earnings and profits of the controlled foreign corporation described in section 959(c)(3), determined— (i) as of the close of the taxable year described in subparagraph (A), (ii) without diminution by reason of distributions made during such taxable year, and (iii) without regard to this paragraph. For purposes of this chapter, any determination with respect to the treatment of distributions described in clause (ii) shall be made after the application of this paragraph to the earnings and profits described in the matter preceding clause (i). (C) Undistributed U.S. earnings The term