Treas. Reg. § 1.1092(d)-2 Personal property.

(a) Special rules for stock. Under section 1092(d)(3)(B), personal property includes any stock that is part of a straddle, at least one of the offsetting positions of which is a position with respect to substantially similar or related property (other than stock). For purposes of this rule, the term substantially similar or related property is defined in § 1.246-5 (other than § 1.246-5(b)(3)). The rule in § 1.246-5(c)(6) does not narrow the related party rule in section 1092(d)(4).

Reads the regulation as written; whether it still defines the term for current § 1092(d)(3)(A)(i) is unsettled. It operates under § 1092(d)(3)(B), rewritten by Pub. L. 108-357, § 888(c)(1) (2004), unamended since T.D. 8590 (1995); the 2004 reports intend it to continue (H.R. Rep. No. 108-755, at 757 n. 867; JCS-5-05, at 485 n. 975); no court or ruling applying it under the current clause was found (SIH Partners, 167 T.C. No. 8 (2026), is a § 246(c) case). The regulation requires the offsetting position be in substantially similar or related property “(other than stock)”; current § 1092(d)(3)(A)(i) has no such words, so a short in another issuer's stock may be a straddle under the statute and not under the regulation. No § 1092 case or ruling on this was found

(2) Special rule for certain straddles. This section applies to positions established after March 1, 1984, if the taxpayer substantially diminished its risk of loss by holding substantially similar or related property involving the following types of transactions—