Half Billion Dollar Bank Heist?

The Wall Street Journal is reporting that Mt. Gox has "lost" 850,000 bitcoins worth about $473 million today or $975 million about 3 months ago according to CoinDesk. To put that in perspective, the most expensive diamonds in the world, The Cullinan diamond and the more famous Hope Diamond, are less than the lower loss estimate. Somewhere along the way, Mt. Gox lost the equivalent of about two Hope Diamonds.

Was this "lost" as in the disk was corrupt and they had no backup? Or "lost" as in their software was bad and information fell into the ether? Or "lost" as in "stolen" where someone has them? There is a lot of speculation but no clear answers.

When was the last time you heard of a half billion dollar bank heist?

I wonder if this will be turned into a movie?