(a) Securities, other than those referred to in section 515 of this title, held by an insurer shall be valued, in the discretion of the Commissioner, at their market value, or at their appraised value, or at prices determined by him as representing their fair market value, all consistent with any current method for the valuation of any such security formulated or approved by the National Association of Insurance Commissioners.
(b) Preferred or guaranteed stocks or shares while paying full dividends may be carried at a fixed value in lieu of market value, at the discretion of the Commissioner and in accordance with such method of computation as he may approve.
(c) The stock of a subsidiary of an insurer shall be valued on the basis of the value of only such of the assets of such subsidiary as would constitute lawful investments for the insurer if acquired or held directly by the insurer.