I think my worst trading decision is EMC2. LOL. I spent about 0.2 BTC to buy EMC2 when its price was only 0.00001 BTC/EMC2 then I sold it for 0.00002 BTC/EMC2. Also I doubled all my money but if I were more patient at the time maybe I would have earned more than that 7 or 8 times cause only 1 month after that EMC2 price rised to more than 0.0001 BTC