Mumbai: The Samvat 2068 began on a sombre note as the country's premier stock exchange BSE Ltd today decided to annul all the derivatives trades transacted during the ''Muhurat'' trading due to large movement of the Sensex Futures. "Trading members of the Exchange were informed that due to large movement of Sensex futures observed during the special session conducted as Muhurat trading for Diwali, BSE has decided to annul all the derivatives trades done on October 26, 2011 under Bye Law 1.46 of Derivatives segment," BSE said in a statement here. The Exchange said that it has also suspended a member broker from trading any further in the proprietary position on the Exchange in all segments and has launched a detailed investigation into the matter. Meanwhile, the BSE Sensex shed most of intra-day gains on ''Muhurat'' trading of Samvat 2068 and closed on a flat note with positive bias in the equity segment today. At the traditional Muhurat trading session, the BSE Sensex opened about 70 points up, but the gains petered out after a while. The index closed at 17,288.83 points, barely 33.97 points above the previous day. Earlier, Lakshmi Pooja at BSE was graced by personalities from the fields of broking, corporates and Bollywood. Actress Mahima Choudhary was present at the Exchange for the ''Opening Bell''.