By Andrea Tryphonides Of DOW JONES NEWSWIRES LONDON (Dow Jones)--Citigroup Inc. (C) began placing 8 million shares in medical devices developer Smith & Nephew PLC (SN.LN) Wednesday, according to several London-based traders. Traders said the placing is being conducted at a price of 559 pence a share. At 0855 GMT, Smith & Nephew shares were down 3.9% at 564.0 pence, leading the blue-chip decliners in London. The shares were underperforming the FTSE 100, which was 1.6% higher at 5219.30. -By Andrea Tryphonides, Dow Jones Newswires; +44-20-7842-9281; [email protected] (END) Dow Jones Newswires July 21, 2010 05:07 ET (09:07 GMT)