Mt. Gox was the largest Bitcoin exchange in the world. By early 2014 it handled roughly 70% of all global BTC trading volume. On February 7, 2014, it suspended withdrawals. Three weeks later, on February 28, it filed for bankruptcy in Tokyo and announced that approximately 850,000 BTC, customer deposits, were missing. More than a decade later, repayments are still being processed.
The collapse fundamentally reshaped how the industry thought about exchange custody. The catchphrase "not your keys, not your coins" comes directly from this incident.
The state of the chain that day
Mt. Gox suspended withdrawals on February 7, 2014. That day's Bitcoin blocks were around height 285,000-286,000. Pull a representative block to anchor the timeline:
Bitcoin's price the day before the suspension was around $830. By the time bankruptcy was declared three weeks later, the market price had dropped below $580. The contagion sentiment was real.
The "200,000 BTC found"
On March 20, 2014, Mt. Gox announced they had located 200,000 BTC in an old wallet they'd forgotten about. (This is real. This actually happened.) These coins moved from cold storage to escrow accounts under the trustee's control. They became the foundation of the eventual creditor distribution.
The remaining ~650,000 BTC was never recovered. Some research has connected portions of it to the Russian-attributed BTC-e exchange and individuals indicted by US prosecutors in 2017, but most of the coins are still formally unaccounted for.
A decade of bankruptcy court
Japanese bankruptcy law required creditors to claim the value of their BTC at the time of bankruptcy, in yen. Bitcoin's price had risen by the time the trustee actually had assets to distribute, which created a paradox: the recovered 200,000 BTC was worth far more in yen than the total claims. Creditors successfully petitioned for a switch to Civil Rehabilitation in 2018, which let them recover BTC pro-rata rather than in fixed yen amounts.
Distribution began in 2024. Pull a recent block to ground yourself in the "now" of this story:
Roughly 12 years between bankruptcy and the start of repayment. For a creditor who held a 1 BTC claim, the recovery is economic in dollar terms (and then some), but the optionality cost of not having the coins for 12 years is enormous.
On-chain footprints
Mt. Gox's known cold-storage clusters (identified through community forensics over the years) have been monitored continuously by chain analysts. Every batch of repayments creates large transactions to centralized exchanges for redistribution. These show up as significant flows on chain whenever they happen.
Our future Address Monitoring API will surface these flows in real time once Phase 2 ships.
The lessons
- Custody risk is real. If you hold significant BTC on an exchange, you don't own BTC. You own an IOU on an exchange that may or may not be solvent.
- Solvency is provable on chain. Modern proof-of-reserves attestations exist precisely because of Mt. Gox. They aren't perfect, but they're a meaningful improvement.
- The chain remembers. Every transaction Mt. Gox ever made is still publicly visible. Forensic analysis 10+ years later is still producing new findings about where the missing coins went.
The 200,000 BTC the trustee recovered, the years of legal process, the eventual partial repayments, all of it leaves a trail you can follow block by block. That auditability is the entire point.
Read more: The Block Size War, The Inflation Bug, or 10,000 BTC for Two Pizzas.