Short Final Year Exception & Asset Sales

How would you address this hypo?

S is in a parent-sub controlled group with 6 subsidiaries: C, D, E, F, & G.

S will sell to B all of S's assets in subs C through F. All of those subs' employees will work for B post-sale. At an uncertain future date, S will sell G's assets to B. At no point will S become part of B's controlled group. 

S participates in a multi-employer DC Plan with Z. They are the only two participating employers. S controls all aspects of the Plan. S owns a small stake in Z, but not enough to bring Z into S's controlled group. S's plan operates on a fiscal year, ending on 9/30. The plan uses a NEC SH. The plan will continue NEC contributions for the upcoming plan year.

If S were to terminate its plan on 10/20, the date of closing, or shortly thereafter would it qualify for the IRC § 410(b)(6)(C) short final year exception for the NEC SH, despite no change in controlled group?

Likewise, S will no longer own any part of Z as of 12/31. Does this change your analysis at all? 

I'm stumped on this because Treas. Reg. § 1.410(b)-2(f) states that an asset sale qualifies under 410(b)(6)(C), however Section 410(b)(6)(C) also states that a change in controlled group must occur for the exception to apply. It just does not make a lot of sense for an asset sale to qualify under 410(b)(6)(C) when asset sales infrequently result in controlled group changes, as the seller remains intact immediately post-closing.

My hunch is that 410(b)(6)(C) does not apply for either the 10/20 asset sale because no change in controlled group will occur, and that the sale of S's interest in Z to Z's other owners does not alter this analysis.