US investment bank JP Morgan & Co has been fined £350,000 for breaching London Stock Exchange rules against trades designed solely to manipulate stock index levels, the Exchange said yesterday. The exchange said J.P. Morgan had acknowledged breaking its rule 2.10 against index manipulation and had agreed to the fine.

The move comes after a shock late decline in the blue-chip FTSE 100 index on November 28th. The index tumbled 38 points in the final minute of trade, because of two relatively small trades in Glaxo Wellcome and SmithKline Beecham. Two JP Morgan traders were subsequently suspended over the trades.