A document circulating widely in the Bitcoin world said the company had lost 744,000 Bitcoins in a theft that had gone unnoticed for years. That would be about 6 percent of the 12.4 million Bitcoins in circulation. While Mt. Gox did not respond to numerous requests for comments, and the companies issuing the statement scrambled to determine the exact situation at Mt. Gox, which is based in Japan, the news helped push the price of a single Bitcoin below $500 for the first time since November, when it began a spike that took it above $1,200.
