European shares faced the biggest decrease in value during the last month due to the growing concern regarding Greece leaving the Euro zone, while European countries' leaders were meeting in Brussels. The Stock Exchange Group(Plc) in London fell the most during two an a half years, following a sale made by UniCredit (SpA) and Intesa Sanpaolo (SpA) of their combined stake, which constitutes 11.5%. Two companies, Petropavlovsk (Plc) and Vedanta Resources (Plc), faced a slump in basic resources' values, such as gold and copper. The European Stock Index 600 (SXXP) lost 2.1 per cent of the share's price, falling to the level of 239.51 at the end of the trading session, being a biggest dip since the 23th of April.