Any domestic insurer and any foreign or alien insurer authorized to do business in this state may retain, invest in, or acquire the whole or any part of the capital stock of any other insurer, or have a common management with any other insurer, provided such retention, investment, acquisition, or common management is not inconsistent with any other law relating to the investment of the funds of domestic insurers, and provided further that by reason of such retention, investment, or acquisition of such capital stock, or common management, the business of such insurers with the public shall not be conducted in a manner which substantially lessens competition generally in the business of insurance or creates a monopoly therein.