(a) This account must include the book cost of investments in securities issued or assumed by non-associate companies, investment advances to these companies, and any investments not accounted for elsewhere. This account must also include unrealized holding gains and losses on trading and available-for-sale types of security investments. Include also the offsetting entry to the recording of amortization of discount or premium on interest bearing investments. (See account 419, Interest and dividend income (§367.4190).)

(b) The records must be maintained in a manner so as to show the amount of each investment and the investment advances to each person.