NEW YORK , May 3, 2024 /PRNewswire/ -- S&P MidCap 400 constituent Vistra Corp. (NYSE: VST) will replace Pioneer Natural Resources Co. (NYSE: PXD) in the S&P 500, S&P SmallCap 600 constituent Aaon Inc. (NASD: AAON) will replace Vistra in the S&P MidCap 400, and Marathon Digital Holdings Inc. (NASD: MARA) will replace Aaon in the S&P SmallCap 600 effective prior to the opening of trading on Wednesday, May 8 . S&P 500 and S&P... Read More