An anonymous reader shares a report: The hundreds of prize payouts were mostly just a few bucks each, part of a promotional campaign by a South Korean cryptocurrency exchange. The total reward pot: 620,000 Korean won, or about $425. Then came a colossal mistake. A staffer for Bithumb, South Korea's No. 2 crypto exchange, didn't distribute 620,000 Korean won. Rather, the prizes, due to an input error, emerged in a different currency: 620,000 bitcoins, valued at more than $40 billion.

That meant a winner who should have received a sum of 2,000 won -- enough to buy a cheap cup of coffee -- reaped, at least momentarily, more than $120 million in bitcoins. Enough recipients sought to sell or wi...