OK, so I still don't think what you're describing could be profitably executed. But playing devil's advocate... > Crashing BTC with stolen BTC is free. Yes, a

OK, so I still don't think what you're describing could be profitably executed. But playing devil's advocate... > Crashing BTC with stolen BTC is free. Yes, agree that you could definitely crash the bid price by dumping 50k stolen BTC. This might also happen naturally if someone holding lots of BTC is forced to sell to get USD quick (e.g. "oh no, huge unexpected medical bill, tax bill, fine..."). [Not sure it's "free" though; what about opportunity cost?] > The presumption is that a lot of people right now would sell their BTC when they see BTC drop down to $5. People panic when they see losing value... and you buy back the BTC you sold at that point. So during your buyback, you'll be bidding against all the bitcoin loons who also want to buy after you crashed the price. These people are just irrationally exuberant about internet play money and have been waiting for the price to hit $5 or $10 again. You also have to convince the other loons who are holding lots of BTC that their play money is now worthless. You need to convince them to put down the cheetos, transfer BTC to mtgox and plug those sell orders in there. I'm not convinced crashing the bid price alone would be enough to achieve that. As well as manipulating price, you also need to kill the enthusiasm and belief. I think to really trigger some selling for your buyback, you would want to carry out a smear campaign at the same time. You want to inject some fake news articles (either via hacking or social engineering) and create confusion on the forums. Convince people that bitcoin is doomed (e.g. "all BTC exchanges to be illegal, say regulators"). Or that you have a technical attack on the network. Pub the articles first, smear forums, then DoS forums (to prevent corrections), then trigger the "mother sell"... that would give you the best chance of success for the attack you are thinking of. </devilsadvocate> What I wanted to finish with though, is that anyone trying to pull something this would have to actually believe that BTC are valuable, or equivalently that suckers will pay more for them later. Otherwise they wouldn't be buying them back.