Section 40. Every society shall invest its funds in securities permitted by chapter one hundred and seventy-five for the investment of the capital of insurance companies, except that it may invest its funds in the shares or savings deposits of federal savings and loan associations located in the commonwealth, in shares or deposits in credit unions insured by the Massachusetts Credit Union Share Insurance Corporation and, in addition, invest and deposit in paid-up shares and accounts of and in co-operative banks chartered by the commonwealth, and may deposit any of its funds in savings accounts in any savings bank or trust company, chartered under the laws of the commonwealth; provided, that any foreign society permitted or seeking to do business in the commonwealth may invest its funds in accordance with the laws of the state where it is incorporated; and provided, further, that a part thereof, not exceeding twenty per cent of its death fund, may be invested in a building for use and occupation by the society as its home office; and that a society having branches situated in the Dominion of Canada may invest a part of its death fund in the public funds of the Dominion of Canada, or of any province of the Dominion of Canada, not exceeding in the aggregate an amount equal to the sum of its collected premiums for the four months last past. Any society, having admitted assets as shown by its annual statement filed with the commissioner in excess of one hundred and five per cent of it entire liabilities, including its required reserves, provided such reserves are at least equivalent to the amount required by the American experience table of mortality with interest at two and one half per cent per annum, may invest an amount not exceeding five per cent of its funds in the capital stock of a trust company incorporated in and doing business in the commonwealth, or of a national banking association incorporated under federal law and located in any one of the New England states, if such trust company or association has paid dividends in cash of not less than four per cent on its capital stock in each of the five years next preceding the date of the investment, and if the amount of surplus of such trust company or association is at least equal to fifty per cent of the amount of its capital stock. Any society, having admitted assets as shown by its annual statement filed with the commissioner in excess of one hundred per cent of its entire liabilities, including its required reserves, provided such reserves are at least equivalent to the amount required by the American Experience Table of Mortality with interest at two and one half per cent per annum, may invest an amount not exceeding twenty-five per cent of such excess in the shares of stock of companies incorporated under the laws of the United States, or any state thereof, or in the certificates of beneficial interest issued by an association or trust as defined in section one of chapter one hundred and eighty-two; provided, that the owners or holders of such stock or certificates may not become liable to any assessment except for taxes. No society shall invest in, acquire, or hold directly or indirectly, more than ten per cent of the capital stock of any corporation, or of the certificates of any association or trust; nor shall more than ten per cent of the society's funds be invested in the stock of any one corporation or in the shares of any one association or trust.