(1) A credit union may invest up to 20 percent of its net worth, per issuer, in corporate bonds.

(2) These bonds must be investment grade, i.e., rated in one of the four highest grades by a recognized national investment rating organization.

(3) Other rating services may be used if the gradations are equivalent to those above, and the rating services are identified by the credit union's investment policy.

(4) Corporate bonds must be reviewed as necessary to assure the credit union's board of directors that bond quality has not fallen below investment grade.