S&P Dow Jones Indices to adjust S&P 500, S&P MidCap 400, and S&P SmallCap 600 indices on Sept 23, ensuring market cap representation. Palantir, Dell, and Erie Indemnity to join S&P 500, replacing American Airlines, Etsy, and Bio-Rad Laboratories. American Airlines to replace TEGNA in S&P MidCap 400, and TEGNA to replace Designer Brands in S&P SmallCap 600. Etsy to replace Haverty Furniture in S&P SmallCap 600. Bio-Rad Laboratories to replace Erie Indemnity in S&P MidCap 400.