Section 15C. An entity that may invest pursuant to section 15A or the legal list may invest in bonds, notes or other interest-bearing obligations of the following classes:

(i) direct obligations of the United States or in obligations that are unconditionally guaranteed as to the payment of principal and interest by the United States;

(ii) legally issued, assumed or unconditionally guaranteed bonds, notes or other interest-bearing obligations of the commonwealth, including legally issued bonds, notes or other indebtedness of an entity established as a public instrumentality by general or special law;

(iii) legally issued, assumed or unconditionally guaranteed bonds, notes or other interest-bearing obligations of any state other than the commonwealth which has, not within the 20 years prior to making the investment, defaulted for a period of more than 120 days in the payment of any part of either principal or interest of any legally issued or assumed obligation; provided, however, that the full faith and credit of the state shall be pledged for the payment of the principal and interest of the obligations;

(iv) bonds, notes or other obligations issued or guaranteed as to both principal and interest by the Dominion of Canada or any of its provinces; provided, however, that (A) the bonds, notes or obligations shall be payable in United States funds either unconditionally or at the option of the holder of the bonds, notes or other obligations; and (B) at the date of investment the Dominion of Canada or the applicable province shall not have been in default in the payment of interest or principal of any of its obligations for a period in excess of 31 days at any time within the 20 years preceding such date of investment. Not more than 5 per cent of the assets of an entity authorized to invest pursuant to section 15A or the legal list may be invested in obligations authorized under this paragraph;

(v) bonds, notes or obligations issued, assumed or guaranteed by the International Bank for Reconstruction and Development, the Inter–American Development Bank or the Asian Development Bank containing an unconditional promise to pay or an unconditional guarantee of the payment of the interest on the bonds, notes or obligations regularly and the principal of the bonds, notes or obligations by a specified date in United States currency; provided, however, that not more than 3 per cent of the assets of an entity authorized to invest pursuant to section 15A or the legal list shall be invested in the bonds, notes or obligations; and provided further, that the commissioner may at any time on the commissioner's own initiative suspend the authorization granted by this clause for periods as the commissioner may determine;

(vi) obligations of or instruments issued by and fully guaranteed as to principal and interest by the Federal National Mortgage Association established under the federal National Housing Act, 12 U.S.C. 1715 et seq.;

(vii) debentures, bonds or other obligations issued by any federal home loan bank or consolidated federal home loan bank debentures or bonds issued by the federal home loan bank board under the Federal Home Loan Bank Act, 12 U.S.C. 1421 et seq.;

(viii) debentures issued by the Central Bank for Cooperatives or consolidated debentures issued by the Central Bank for Cooperatives and the 12 Regional Banks for Cooperatives under the federal Farm Credit Act of 1933, 12 U.S.C. 1131 et seq.;

(ix) collateral trust debentures or other similar obligations issued by any federal intermediate credit bank or consolidated debentures or other similar obligations issued by the federal intermediate credit banks under the Federal Farm Loan Act, 12 U.S.C. 742 et seq.;

(x) farm loan bonds issued by any federal land bank under said Federal Farm Loan Act;

(xi) promissory notes representing domestic farm labor housing loans authorized under federal law when the notes are fully guaranteed as to principal and interest by the Farmers Home Administration of the United States Department of Agriculture;

(xii) bonds, notes or obligations issued, assumed or guaranteed by the Export–Import Bank of the United States;

(xiii) obligations of any person, including any form of mortgage-backed security, as to which the payment of principal and interest according to the terms of the obligations shall be guaranteed by the Government National Mortgage Association under said federal National Housing Act;

(xiv) certificates issued by the Federal Home Loan Mortgage Corporation representing interests in mortgage loans made, acquired or participated in by the Federal Home Loan Mortgage Corporation; and

(xv) system-wide obligations issued under the Farm Credit Act of 1971, 12 U.S.C. 2001 et seq., by institutions included in the federal farm credit system.