Mt. Gox

A buy order was executed partially or in full when the price bid could be matched against a sell order that was at or below the bid amount. A sell order was executed partially or in full when the price asked could be matched against a buy order that was at or above the ask amount. Orders that could not be matched immediately remain in the orderbook.

Unfunded orders did not appear in the order book, but were automatically inserted when a deposit was credited. For example, Mt. Gox allowed the entry of a "buy" order even if the account had insufficient funds. If possible, Mt. Gox would execute a portion of the order if it could be partially funded. If a deposit was later credited and the deposit resolves the insufficient funds status of an outstanding order, the order would be immediately activated, and if possible, executed.

Mt. Gox charged a trading fee of up to 0.6% from each party of successful trades made through the market. The fee appeared in the account history next to each trade. The trading fee was discounted for larger customers based on volume, which was calculated as a sliding window over the last 720 hours (30 days).

The fees were, by default, subtracted from the proceeds of each trade (e.g., a buy of 1.0 BTC will add to the account balance 0.994 BTC when the exchange fee is 0.6%). An account setting would allow fees to be added to the purchase amount instead (e.g., buying 1.0 BTC at $5 will cost about $5.03 when the exchange fee is 0.6%).

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 on the Mt. Gox exchange, after a hacker allegedly used credentials from a Mt. Gox auditor's compromised computer illegally to fabricate a large number of bitcoins for himself. He used the exchange's software to sell them all nominally, creating a massive "ask" order at any price. The price eventually corrected to its correct user-traded value.[6][7][8][9][10][11][12] Accounts with the equivalent of more than $8,750,000 were affected.[9] In order to prove that Mt.Gox still had control of the coins, the move of 424,242 bitcoins from "cold storage" to a Mt.Gox address was announced beforehand and executed in Block 132749.[13] It was later revealed that the coins may have never been in cold storage, as the proof-of-solvency transaction was broadcast through a remote Linux desktop and a single hot wallet.[14]

In October 2011, about two dozen transactions appeared in the block chain (Block 150951)[15] that sent a total of 2,609 BTC to invalid scripts. As they were impossible to satisfy/redeem, these Bitcoins were effectively destroyed.

On 22 February 2013, following an introduction of new anti-money laundering requirements by Dwolla, some Dwolla accounts became temporarily restricted. As a result, transactions from Mt. Gox to those accounts were cancelled by Dwolla. The funds never made it back to Mt. Gox accounts. Mt. Gox help desk issued the following comment: "Please be advised that you are actually not allowed to cancel any withdrawals received from Mt. Gox as we have never had this case before and we are working with Dwolla to locate your returned funds." The funds were finally returned on May 3, more than 3 months later, with a note "Please be advised never to cancel any Dwolla withdrawals from us again".

In March 2013, the new 0.8.0 version of Bitcoin Core temporarily forked off the main blockchain using differing rules on how transactions could be accepted. The Mt. Gox bitcoin exchange briefly halted bitcoin deposits. Bitcoin prices briefly dipped by 23% to $37 as the event occurred[16][17] before recovering to their previous level in the following hours, a price of approximately $48.[18]

Mt. Gox suspended trading on 11 April 2013 until 12 April 2013 2 am UTC for a "market cooldown".[19] The value of a single bitcoin fell to a low of $55.59 after the resumption of trading before stabilizing above $100. Around mid May 2013, Mt. Gox traded 150,000 bitcoins per day per Bitcoin Charts.[20]

Mt. Gox suspended withdrawals in US dollars on June 20, 2013.[21] The Mizuho Bank branch in Tokyo that handled Mt. Gox transactions pressured Mt. Gox from then on to close its account.[20] On July 4, 2013, Mt. Gox announced that it had "fully resumed" withdrawals, but as of September 5, 2013, few US dollar withdrawals had been successfully completed.[22][23][24]

On August 5, 2013, Mt. Gox announced that they incurred "significant losses" due to crediting deposits which had not fully cleared and that new deposits would no longer be credited until the funds transfer was fully completed.[25]

On 2 May 2013 CoinLab filed a $75 million lawsuit against Mt. Gox alleging a breach of contract.[26] The companies had formed a partnership in February 2013 under which CoinLab handled all of Mt. Gox's North American services.[26] CoinLab's lawsuit contends that Mt. Gox failed to allow them to move existing U.S. and Canadian customers from Mt. Gox to CoinLab.[26]

On 15 May 2013 the US Department of Homeland Security (DHS) issued a warrant to seize money from Mt. Gox's US subsidiary's account with payment processor Dwolla.[27] The warrant suggests the US Immigration and Customs Enforcement, an investigative branch of the DHS, felt that the subsidiary, which was not licensed by the US Financial Crimes Enforcement Network (FinCEN), was operating as an unregistered money transmitter in the US.[27][28] Between May and July more than $5 million were seized. [20] On 29 June 2013, Mt. Gox received its money services business (MSB) license from FinCEN.[28]

Wired Magazine reported in November 2013 that customers were experiencing delays of weeks to months in withdrawing funds from their accounts.[29] The article said that the company had “effectively been frozen out of the U.S. banking system because of its regulatory problems”. Customer complaints about long delays were mounting as of February 2014, with more than 3300 posts in a thread about the topic on the BitcoinTalk online forum.[30]