(Updates with the latest stock movement in the first paragraph and headline.)
Tenable (TENB) shares were up roughly 13% in Thursday trading after the S&P Dow Jones Indices said Wednesday the company will join the S&P SmallCap 600 index before the market opens on Aug. 31.
Tenable will replace Leggett & Platt (LEG), which is being acquired by Somnigroup International (SGI), according to the statement.
Price: $38.08, Change: $+4.42, Percent Change: +13.13%