Where there is at any time—
an alteration in so much of a close company's share or loan capital as does not consist of quoted shares or quoted securities
an alteration in any rights attaching to unquoted shares in or unquoted debentures of a close company,
the alteration shall be treated as having been made by a disposition made at that time by the participators, whether or not it would fall to be so treated apart from this section, and shall not be taken to have affected the value immediately before that time of the unquoted shares or unquoted debentures.
In this section "alteration" includes extinguishment.
The disposition referred to in subsection (1) above shall be taken to be one which is not a potentially exempt transfer