On 19 June 2011, a security breach of the Mt.Gox bitcoin exchange caused the nominal price of a bitcoin to fraudulently drop to one cent...
In July 2011, the operator of Bitomat, the third largest bitcoin exchange, announced that he lost access to his wallet.dat file with about 17,000 bitcoins (roughly equivalent to 220,000 USD at that time)....
In August 2011, MyBitcoin... declared that it was hacked... leaving more than 78,000 bitcoins (roughly equivalent to 800,000 USD at that time) unaccounted for...
In early August 2012... Bitcoinica was hacked twice in 2012, which led to allegations of neglecting the safety of customers' money and cheating them out of withdrawal requests.
In late August 2012, an operation titled Bitcoin Savings and Trust was shut down by the owner, allegedly leaving around 5.6 million USD in bitcoin-based debts...
In September 2012, Bitfloor... reported being hacked, with 24,000 bitcoins (roughly equivalent to 250,000 USD) stolen.
On 3 April 2013, Instawallet, a web-based wallet provider, was hacked, resulting in the theft of over 35,000 bitcoins. With a price of 129.90 USD per bitcoin at the time, or nearly 4.6 million USD in total...
On 11 August 2013, the Bitcoin Foundation announced that a bug in a pseudorandom number generator within the Android operating system had been exploited to steal from users' wallets...
A Bitcoin bank, operated from Australia but stored on servers in the USA, was hacked on 23 and 26 October 2013, with a loss of 4100 Bitcoins, or over 1 million AUD.
In Hong Kong a Bitcoin trading platform owned by Global Bond Limited (GBL) vanished with 30 million yuan(US$5 million) from 500 investors on 26th October 2013.