Mt. Gox

In the early 2010s, Tokyo-based Mt. Gox was the largest Bitcoin exchange in the world. Its collapse is the textbook example of what can happen when your bitcoin are held by a third party.^[1]

1. 7 February 2014

   Withdrawals halted

   Mt. Gox halts all bitcoin withdrawals.

2. 28 February 2014

   Bankruptcy filing

   Around 850,000 BTC are missing – about 750,000 belonging to customers and 100,000 to the company.

3. 20 March 2014

   Partial find

   Just under 200,000 BTC turn up again in an old wallet.

4. 20 October 2021

   Rehabilitation plan

   Creditors approve the repayment plan, and the Tokyo District Court confirms it the same day.^[2]

5. 5 July 2024

   First repayments in bitcoin

   The first creditors receive bitcoin and Bitcoin Cash.^[3]

According to later analyses, most of the bitcoin had been stolen gradually from the hot walletGlossaryHot walletA wallet whose private keys are stored on a device connected to the internet – such as a smartphone app. Handy for payments and small amounts, but more exposed to online attacks than cold storage.On the learning path: Stage 5 · Step 1 – Understanding custody →In the glossary →× from late 2011 onwards – long before the loss became public.^[1]

Still not concluded

According to the trustee, creditors who have completed all the formalities have largely been repaid; many others are still waiting. On 27 October 2025, he extended the deadline for these repayments to 31 October 2026, Japan time (as of September 2026).^[4]

The lesson for you

If your bitcoin are on a platform, the platform holds the keys, and you depend on the bitcoin actually being there. Authorisation under MiCAGlossaryMiCA (Markets in Crypto-Assets Regulation)The EU regulation on markets in crypto-assets. Since 30 December 2024, exchanges, brokers and custodians in the EU have needed authorisation; the last transitional period ended on 1 July 2026. MiCA regulates providers, not Bitcoin itself.On the learning path: Stage 4 · Step 2 – Choosing a provider →In the glossary →× and keeping customer assets separate reduce this risk in the EU but don’t eliminate it. Hence the saying ‘Not your keys, not your coins’GlossaryNot your keys, not your coinsA guiding principle of the Bitcoin community: if you don’t hold the private keys yourself, you don’t own your bitcoin directly – you only have a claim against the custodian. Exchange collapses such as Mt. Gox and FTX show why.On the learning path: Stage 5 · Step 1 – Understanding custody →In the glossary →× – more in Understanding custody.