As previously discussed, Baxter International (BAX) will be spinning off Baxalta (BXLT) after the close of business on June 30. As is often the case with larger spinoffs this will result in some S&P index reshuffling. First, Baxter will no longer be large enough to remain a member of the S&P 100 and will be replaced by Priceline (PCLN).
Baxalta will be a large baby, joining the S&P 500 immediately after its birth. It will replace QEP Resources(QEP), which was spun out of Questar (STR) back in 2010 and was one of the first spinoffs covered by this site. QEP will move down to the S&P MidCap 400, replacing Itron (ITRI). Itron will move down to the S&P SmallCap 600 replacing Arch Coal (ACI).
Disclosure: The author holds no position in any stock mentioned