26 CFR § 1.1091-2
Basis of stock or securities acquired in “wash sales”
June 25, 2020
(a) In general. The application of section 1091(d) may be illustrated by the following examples:
Example 1. A purchased a share of common stock of the X Corporation for $100 in 1935, which he sold January 15, 1955, for $80. On February 1, 1955, he purchased a share of common stock of the same corporation for $90. No loss from the sale is recognized under section 1091. The basis of the new share is $110; that is, the basis of the old share ($100) increased by $10, the excess of the price at which the new share was acquired ($90) over the price at which the old share was sold ($80).
Example 2. A purchased a share of common stock of the Y Corporation for $100 in 1935, which he sold January 15, 1955, for $80. On February 1, 1955, he purchased a share of common stock of the same corporation for $70. No loss from the sale is recognized under section 1091. The basis of the new share is $90; that is, the basis of the old share ($100) decreased by $10, the excess of the price at which the old share was sold ($80) over the price at which the new share was acquired ($70).
(b) Special rule. For a special rule as to the adjustment to basis required under section 1091(d) in the case of wash sales involving certain regulated investment company stock for which there is an average basis, see paragraph (e)(3)(iii) (c) and (d) of §1.1012-1.
[T.D. 6500, 25 FR 11910, Nov. 26, 1960, as amended by T.D. 7129, 36 FR 12738, July 7, 1971]