Section 15B. (a) The legal list prepared pursuant to section 15A may include securities that are approved for investment in accordance with this section.

(b) The securities eligible for approval for investment under this section may include: (i) interest-bearing obligations of any state, county, city, town or district or any subdivision or instrumentality thereof and any authority established under the laws of the United States or any state, county, town or district, including obligations of any of the foregoing payable from specified revenues; (ii) interest-bearing obligations of any corporation organized under the laws of the United States or any state and of any association, the business of which is conducted or transacted by trustees under a written instrument or declaration of trust, having its principal place of business in the commonwealth; and (iii) preferred and common stock of any corporation described in clause (ii). Obligations eligible pursuant to clauses (i) and (ii) shall have an initial offering of at least $50,000,000 and be rated at least a single A.

(c) Upon application by 3 credit unions which have been chartered pursuant to chapter 171, which have submitted in the form and under the conditions as the commissioner may require, requesting authority to invest their deposits and the income derived from their deposits in any of the interest-bearing obligations or stocks referred to in subsection (b), the credit unions may request that the commissioner, in the form and under the conditions as the commissioner may require, authorize, notwithstanding any general or special law to the contrary, the investment in the interest bearing obligations or stock.

(d) If the commissioner grants the authority, the commissioner shall immediately add the name of the investment to the legal list. At any time after adding the name of the investment to the legal list, the commissioner may on the commissioner's own initiative revoke that authority.

(e) If the commissioner authorized investment in an issue of bonds in accordance with this section and, if after the authorization but before the authorization is revoked the issuer shall issue bonds, the proceeds of which shall be used solely to refund the issue previously authorized for investment or another issue of equal or shorter maturity and of equal or prior security and, if the new bonds shall be of equal security with the previously authorized issue and of equal or shorter maturity, the commissioner may authorize investment in the refunding bonds and after the authorization may revoke the authority on the commissioner's own initiative. If the commissioner authorized investment in an issue of bonds in accordance with this section and, if after the authorization but before the authorization is revoked, the issuer shall issue bonds of which at least 90 per cent of the proceeds shall be used to refund the issue previously authorized for investment or another issue of equal or prior security, the security for the new bonds is not less than that for the previously authorized issue and the commissioner may authorize investment in the new bonds and after the authorization may revoke the authority on the commissioner's own initiative.

(f) In determining that any investments authorized under this section shall be included in the legal list or deleted from the list, the commissioner may employ such expert assistance as the commissioner believes proper or may rely upon information contained in publications which the commissioner believes authoritative.

(g) Not more than 10 per cent of the assets of the entity shall be invested in investments authorized under this section.