If a company incorporated under this subtitle has, prior to April eighteenth, one thousand nine hundred and thirty-two, under any provision thereof, purchased, obtained or invested in bonds secured by mortgages which are first liens upon the properties described in the mortgages and the company has sold or assigned with a guaranty of payment of principal and interest or shall, after April eighteenth, one thousand nine hundred and thirty-two, sell or assign with such guaranty a primary part or portion of any of such bonds and mortgages to a purchaser thereof, retaining the balance of the bond and mortgage itself behind and subordinate to the lien of the purchaser, the company may continue to hold such interest in the bonds and mortgages and thereafter acquire any other interest in the bonds and mortgages. In each case any such interest shall be considered a proper authorized and legal investment under the terms of this subtitle.

Nothing herein contained shall be construed to authorize the retention of subordinate interests in bonds and mortgages hereafter purchased, obtained or invested in.