Tenn. Code § 8-3442
The board shall be the trustee of the several funds created by this chapter and shall have full power to invest and reinvest all funds, except the expense funds, subject to the limitation that no investment shall be made except, upon the exercise of bona fide discretion, in securities which at the time of making the investment are, by statute, permitted for the investment of reserves of any domestic life insurance companies, provided that the total sum invested in common and preferred stocks cannot exceed fifty per cent (50%) of the total of the several trust funds of the state retirement system. Subject to such limitations, the board shall have full power to hold, purchase, sell, assign, transfer, or dispose of any of the securities or investments in which any of the funds created herein have been invested, as well as of the proceeds, of such investments and any moneys belonging to said funds.
T.C.A. § 8-3442