Industrials company Nordson Corp.          NDSN,         -2.23%        will join the S&P 500 index, replacing  Xilinx Inc., S&P Indices said late Thursday. PDC Energy Inc.          PDCE,         +1.44%        will replace Nordson in the S&P MidCap 400 index, the provider said. The changes are effective Feb. 15. Advanced Micro Devices Inc.          AMD,         -5.33%        is buying Xilinx in a deal expected to be completed around Feb. 14. Shares of Nordson rose 1.4% in the extended session after ending the regular trading day down 2.2%.