40 ILCS 5/18-159: No gain or profit on investments.

No trustee or employee of the board shall have any direct interest in the income, gains or profits of any investments made in behalf of the system nor receive any pay or emolument for services in connection with any investment. No such trustee or employee shall become an endorser or surety, or in any manner an obligor for money loaned or borrowed from the system. Whoever violates any of the provisions of this Section is guilty of a petty offense.