Foot Locker Inc. will be added to the S&P MidCap 400 after the close of trading on Friday, July 30. Foot Locker will replace Oxford Health Plans Inc., which was removed from the Index after the close of trading on July 29. Oxford Health Plans is being acquired by S&P 500 constituent UnitedHealth Group Inc. in a transaction anticipated to close before Friday's open of trading. The deal is still subject to certain approvals…