(a) The West Virginia economic development authority may use for any investments authorized by sections seven and seven-a, article fifteen, chapter thirty-one of this code, up to one half of the funds of the state mortgage and industrial development investment pool: Provided, That the economic development authority shall deposit with the treasurer of the state for the credit of the state mortgage and industrial development pool such notes, security interests or bonds issued by the economic development authority evidencing the indebtedness of the authority to the pool.

(b) Such notes, security interests or bonds issued by the authority shall be secured by security equal to or better than one of the three highest rating grades by an agency which is nationally known in the field of rating corporate securities: Provided, That notes, security interests or bonds evidencing indebteness of $2 million or less may be secured by a letter of credit guarantee issued by a bank having an unsecured legal lending limit greater than $1 million.

(c) The interest rate and the maturity dates of the notes, security interests or bonds held by the treasurer for the state mortgage and industrial development investment pool shall be determined by the economic development authority according to the provisions of section eleven, article fifteen, chapter thirty-one of this code: Provided, That such interest rate shall not be less than the prior four-week auction average yield for thirteen-week treasury bills and such rate shall be valid for a term of not more than three years: Provided, however, That the economic development authority may determine a variable rate of interest to be adjusted no less frequently than semiannually, and such variable interest rate shall not be less than the prior four-week auction average yield for thirteen-week treasury bills.