NEW YORK (Standard&Poor's CreditWire) Aug. 4, 1999--Standard&Poor's today affirmed its ratings on United HealthCare Corp. d/b/a UnitedHealth Group (see list). Standard&Poor's also revised its outlook on UnitedHealth Group to stable from negative. In addition, Standard&Poor's assigned its single-'A'-plus financial strength and counterparty credit ratings to various UnitedHealth Group's operating subsidiaries (see list), which are viewed as core to UnitedHealth Group's overall corporate structure. At the same time, Standard&Poor's assigned its single-'A' financial strength ratings to various UnitedHealth Group operating subsidiaries (see list) based on explicit support of these operating units by the parent, United HealthCare Corp. UnitedHealth Group is a national leader, offering health care coverage and related services to