In exercising authority, control, or discretion with respect to the several systems, a fiduciary may not: use the assets of the several systems for the fiduciary's own interest or account; act in a transaction involving the several systems on behalf of a person, or represent a person, if the interests of the person are adverse to the interests of the several systems or the interests of participants; receive any consideration for the fiduciary's own account from a person dealing with the several systems in connection with a transaction involving the assets of the several systems; or become an endorser or surety or, in any manner, an obligor, for money lent to or borrowed from the Board of Trustees.