Nextel Communications Inc, Rutherford, New Jersey is seen as a super-high credit risk by Standard & Poor’s Corp, which has cut the Specialised Mobile Radio operator’s senior unsecured debt rating to triple-C-minus from triple-C-plus. It also cut the ratings of Nextel affiliates to triple-C-minus. The action follows termination of MCI Communications Corp’s proposed $1,300m investment in Nextel, and reflects the high degree of financial risk due to a potential cash shortfall during 1995 and the formidable challenge from the already established cellular telephone market and upcoming Personal Communications Services. Without the cash investment from MCI, Nextel will require alternative financing to accelerate its digital network and achieve a head-start on the new operators, which are expected to be providing service by mid-1997.