NY -- Standard & Poor's CreditWire 12/13/95 -- Standard & Poor's ratings of Union Pacific Corp. remain on CreditWatch with negative implications and its ratings of Southern Pacific Rail Corp. remain on CreditWatch with positive implications (see list below) where they were placed August 4, 1995 following the announcement of an agreement to merge the two companies. About $8 billion of rated debt is affected. Standard & Poor's anticipates that a senior rating of triple-`B' would be assigned to the senior debt of Union Pacific Corp. (UP) and Southern Pacific Rail Corp. (SPRC) if and when the Interstate Commerce Commission (ICC) approves the proposed merger. The rating indication incorporates: -- Near-term deterioration of UP's financial condition; -- Substantial multiyear investment