The treasurer may deposit any portion of public moneys, in the treasurer’s possession, in federally insured banks authorized to accept deposits under N.H. Rev. Stat. § 6:8, I and I-a. At the discretion of the treasurer, balances may be collateralized if those balances are deemed to be significant in relation to the equity position of the federally insured bank. Other conditions being equal, those federally insured banks shall receive preference which allow interest on balances. As used in this section the term “public moneys” shall include the general funds of the state and any funds of which the state treasurer acts as custodian or agent.