I read in your "Statement Regarding Recent DDoS Attacks and Mitigation" release about your plans to support trading of Litecoins, presumably to/from bitcoins and/or to/from other currencies: - https://mtgox.com/pdf/20130424_ddos_statement_and_faq.pdf This concerns me. Certainly you are quite familiar with the concept of a 51% attack. While Bitcoin is also a proof-of-work based decentralized digital currency at risk of suffering a 51% attack, I'm comfortable with the risk. This comfort comes from knowing there is tens of millions of dollars of investment in mining hardware, that its mining pools are relatively mature (i.e., operators are competent, some protections against DDoS exist, a fairly decent number of pools to choose from, etc.) and that there are multiple options for decentralized mining as well. At this point in time, there is not anywhere near the amount of mining capacity and maturity that gives me confidence that Litecoin will not see a 51% attack once there is a sufficient amount of loot from a successful attack that would warrant such an effort. Before launching support for Litecoin what I would like to see Mt. Gox do is publish its policy on what the risks are should a successful 51% attack against Litecoin occur. There might be several scenarios. These include: A.) My Mt. Gox exchange account holds only fiat and bitcoins, and I've never traded for Litecoins. Would I be exposed to any risk of loss to those funds should there be a successful 51% attack against Litecoin? B.) I have a balance of Litecoins and fiat, but had no litecoins deposited to Mt. Gox in any block that was ultimately orphaned as the result of the 51% attack. Would I be exposed to any risk of loss to those funds should there be a successful 51% attack against Litecoin? C.) I had bitcoins and I traded them for Litecoins. Following this trade the attacker released blocks that resulted in a double spend such that the Litecoins I received were from the attcker's account (i.e., Litecoins deposited with a transaction that no longer confirms or was double spent). Following the successful 51% attack against Litecoin, do I still have Litecoins that I can withdraw (or trade back into Bitcoins)? D.) I deposited litecoins from a block that utimately was orphaned as the result of a successful 51% attack against Litecoin. Before the attack I was able to trade those litecoins for bitcoins which remain in my account. After the successful 51% attack against Litecoin, do I stil have the ability to withdraw those bitcoins?