Bitcoin can be manipulated. Manipulation takes place at the exchange of Mt. Gox, this price manipulation is done by two bots and listed as "??" in the user's country. They named this bot "Mark" and "Willy".
Markus buys and sells bitcoins at seemingly random prices and does not pay for transaction fees. After further examination, Mark does not actually pay for Bitcoin received. Mark earns 335,889 bitcoins and is active from February 14, 2013 through September 27, 2013.
Seven hours after Mark becomes inactive, Willy appears with 49 accounts. Each of these Willy accounts sequentially purchases bitcoins worth US $ 2.5 million and then becomes inactive. During this period, bitcoin prices soared.