All companies heretofore or which may hereafter be incorporated for the insurance of owners of real estate, mortgages, and others interested in real estate, from loss by reason of defective titles, liens, and encumbrances, as well as all title insurance and trust companies receiving deposits, heretofore incorporated and authorized by charter or by law to carry on said business, shall, from and after the approval of this act, establish and maintain a reserve fund for the protection of policy holders, in the manner herein provided.