McGruber writes with the news as carried (paywalled) by the Wall Street Journal that Mark Karpeles, who headed bitcoin exchange Mt. Gox, has been arrested by Japanese police: In February 2014, Mount Gox filed for bankruptcy, saying it had lost 750,000 of its customers' bitcoins as well as 100,000 of its own, worth some $500 million at the time. A police spokesman said Mr. Karpelès is suspected of manipulating his own account at the company by making it appear that $1 million was added to it. The BBC reports the arrest as well, and notes that the coins missing from Mt. Gox represent 7% of all Bitcoins in circulation.