LONDON -- Standard&Poor's CreditWire 10/2/97 -- Standard&Poor's today has placed the ratings of Skandinaviska Enskilda Banken (S-E-Banken) and related entities (see list below) on CreditWatch with developing implications. At the same time, the single-'A'-plus claims-paying ability rating of Trygg-Hansa Insurance Co. Ltd. (Trygg-Hansa) has been placed on CreditWatch with negative implications. The rating actions are in response to S-E-Banken's bid for the entire share capital of Trygg-Hansa AB, the parent company of the Trygg-Hansa Group. Standard&Poor's believes that there could potentially be significant synergies arising from a merger of the two organizations, whilst also recognizing the considerable management challenge that the transaction represents. In addition, the deal should create a major player in the