Any personal property or securities lawfully acquired by an insurer, which it could not otherwise have invested in or loaned its funds upon at the time of such acquisition, shall be disposed of within 5 years from date of acquisition, unless within such period the security has attained to the standard of eligibility; except, that any security or personal property acquired under any agreement of bulk reinsurance, merger or consolidation may be retained for a longer period if so provided in the plan for such reinsurance, merger or consolidation as approved by the Commissioner under Chapter 49 of this title. The Commissioner may by order grant, from time to time, reasonable extensions of the period, as specified in any such order, within which an insurer shall dispose of any such property or security.