Module 16: Postmortems
Mt. Gox (2014): When the Biggest Exchange Disappeared
Chapter 2 of 12 · about 4 minutes
2.1 What it was
Mt. Gox was a Tokyo-based exchange, founded in 2010, that grew into the largest Bitcoin exchange in the world. At its peak, it handled a large majority of all bitcoin trading. For many early users, buying bitcoin effectively meant using Mt. Gox.
People trusted it because it was the biggest, the most established, and in the early days, there were few alternatives.
2.2 What happened
| Period | Events |
|---|---|
| 2011 | A security breach led to stolen funds and a temporary crash in the exchange's bitcoin price |
| 2011 to 2013 | Bitcoin was being steadily drained from the exchange's wallets, later found to have happened over several years, apparently without being detected by management |
| 2013 | Customers increasingly complained of long delays withdrawing dollars and bitcoin |
| February 2014 | Mt. Gox halted all bitcoin withdrawals, blaming a technical issue with bitcoin transactions |
| Late February 2014 | Trading stopped, the website went offline, and the company filed for bankruptcy protection in Japan |
Mt. Gox reported that about 850,000 bitcoin were missing, belonging to customers and the company. Around 200,000 were later found in an old wallet. That left about 850,000 − 200,000 = 650,000 BTC never recovered, lost mostly to theft over the preceding years.
2.3 Warning signs
| Warning sign | What it meant | Module |
|---|---|---|
| Long withdrawal delays for months | Often a sign that an exchange lacks the funds it claims (Module 1, Chapter 7) | Module 1 |
| Mt. Gox's price differed from other exchanges | Traders were willing to pay more or accept less to avoid being stuck | Module 1, Chapter 6 |
| No independent verification of reserves | Customers couldn't confirm their coins existed | Module 1, Chapter 7 |
| Concentration of the market in one exchange | Single point of failure for the whole ecosystem | Module 12, Chapter 5 |
| Earlier security breach | Security problems had already occurred | Module 2 |
The price gap deserves attention. Before the collapse, bitcoin on Mt. Gox traded at different prices from other exchanges, because withdrawing was so hard. When an exchange's prices drift away from the rest of the market and arbitrageurs can't close the gap (Module 1, Chapter 6), it often means money can't get out.
"So the market was warning people, through the price," said Mint.
"Markets often know before the headlines do," said Hash.
2.4 Aftermath
The bankruptcy turned into a civil rehabilitation process under the supervision of a Tokyo court. Creditors waited roughly a decade. Repayments in bitcoin and bitcoin cash began in mid-2024, and the trustee reported that around 19,500 creditors had been repaid by 2025.
The repayment deadline was extended several times. In October 2025, it was moved to 31 October 2026, with wallets linked to Mt. Gox still reportedly holding about 34,700 BTC at that time. Check for any updates after October 2026.
Because creditors were repaid partly in bitcoin, and bitcoin's price had risen enormously since 2014, many received more in dollar terms than their original losses were worth at the time. But they waited ten years without access to their funds.
2.5 Lessons
- Not your keys, not your coins (Module 1, Chapter 7). Customers who withdrew to their own wallets weren't affected.
- Withdrawal delays are a serious warning. If an exchange repeatedly delays withdrawals with technical explanations, move funds out while you can.
- Watch for price gaps between an exchange and the wider market.
- Demand proof of reserves, and remember it shows assets, not liabilities (Module 1, Chapter 7).
- Don't concentrate everything on one platform (Module 12, Chapter 5).
2.6 Try it yourself
Find out whether each exchange you use publishes proof of reserves, how often, and whether it includes liabilities. Then compare the BTC price on your exchange with two major exchanges at the same moment. If you saw a persistent gap of several percent, what would you do?
Key takeaways from this chapter
- Mt. Gox was the dominant Bitcoin exchange until its collapse in February 2014, with about 850,000 BTC reported missing.
- Funds had been drained over years without management detecting it.
- Warning signs included long withdrawal delays, price gaps with other exchanges, no reserve verification, and earlier breaches.
- Creditors waited about a decade for repayments, with the deadline extended to 31 October 2026.
- Self-custody, attention to withdrawal delays and price gaps, proof of reserves, and diversification across platforms are the key lessons.