Mt. Gox: how 'not your keys' became a saying.

Mt. Gox started as a trading card marketplace and became the dominant bitcoin exchange without matching controls.

In February 2014 withdrawals stopped and bankruptcy followed; theft had gone unnoticed for years.

There was no separation of client and company assets, no independent balance verification and no reserve audit.

Customers saw a balance on a screen; that balance was not proof of ownership.

Resolution took more than a decade, with creditors repaid in a completely different market.

Even a successful procedure leaves you without access for years.

Hold long-term positions in self-custody and use platforms only for the duration of a trade.

With custodians, look for proof of reserves, segregation and external audit.