After weeks of speculation over its financial health, the beleaguered Bitcoin exchange Mt. Gox has filed for bankruptcy protection. A company lawyer made the announcement at an impromptu news conference held at Tokyo District Court, according to The Wall Street Journal.

850,000 bitcoins were lost

Mt. Gox says it has ¥6.5 billion ($63.9 million) in liabilities with ¥3.84 billion ($37.7 million) of assets at present, and the company has admitted that it has lost a total of 850,000 bitcoins — worth close to $500 million. 750,000 of those belonged to customers, and 100,000 were company assets.

Mt. Gox suspended Bitcoin withdrawals in early February, ultimately blaming a transaction bug that could have led to theft. The exchange went offline altogether on Monday amid reports that 744,000 bitcoins had been stolen. Authorities in the US and Japan are now looking into Mt. Gox's business, it emerged this week.