You must be aware of this at all time, there is a small number of Bitcoins that are available online, and that’s it. This is the main reason for the stability of this currency as well as its value. Spend you Bitcoins carefully, and there is always the same amount of Bitcoins in circulation.
Mt Gox was a company that was handling almost 70% of all the transactions based on Bitcoin, and at the time of the crash, it was holding over 850,000 Bitcoins, which is valued to be the same as 450 million dollars. That accident is considered to be one of the biggest thieveries of all time, and since the Bitcoin is untraceable, they only managed to retrieve 200,000 Bitcoins.