LONDON -- Standard&Poor's CreditWire 7/9/97 -- Standard&Poor's today has assigned its triple-'A' rating to Nippon Telegraph&Telephone Corp.'s (NTT) Y100 billion 2.5% Eurobond issue due July 25, 2007. The rating outlook is negative. The rating is based on NTT's dominant position and important role in the Japanese telecommunications market, as well as its strong financial profile compared with major international peers. Despite increased penetration by Japan's new common carriers, NTT maintains a very strong share in the domestic telephone market. Company earnings are improving as a result of successful rate rebalancing and continued growth in the Japanese cellular phone market. However, the competitive picture of the Japanese telecom industry remains unclear amid ongoing restructuring. New