“Equity security” as used in sections 26.1-05-11 through 26.1-05-15 means any stock or similar security; any security convertible, with or without consideration, into such a security, or carrying any warrant or right to subscribe to or purchase such a security; any such warrant or right; or any other security which the commissioner deems to be of similar nature and considers     necessary or appropriate to treat as an equity security, by any rules the commissioner adopts in the public interest or for the protection of investors.