if the dividend rate of such stock is fixed at not to exceed the legal rate of interest in the State of incorporation or 8 percent per annum, whichever is greater, on the value of the consideration for which the stock was issued, and if substantially all such stock (other than nonvoting preferred stock, the owners of which are not entitled or permitted to participate, directly or indirectly, in the profits of the corporation, on dissolution or otherwise, beyond the fixed dividends) is owned by such association, or members thereof; nor shall exemption be denied any such corporation because there is accumulated and maintained by it a reserve required by State law or a reasonable reserve for any necessary purpose.