Where is MyBitcoin? (the story)
Since then dead, the Bitcoin transaction processor MyBitcoin, on August 2011 had to shut down operations after declaring it was hacked.
Surprisingly they managed to pay 49% of customer deposits, leaving the remaining funds (78,000 bitcoins, then about $800,000) unaccounted for.
You could sell that amount of bitcoins today for a little less than $2,589,490,800.