The Mt. Gox bitcoin exchange in Tokyo filed for bankruptcy protection, acknowledging that a significant amount of the virtual currency had gone missing.

The exchange’s CEO Mark Karpeles appeared before Japanese TV news cameras on Friday, bowing deeply for several minutes.

Speaking in Japanese at a Tokyo court, he apologized for the troubles he had caused to so many people.

Kyodo News said debts at Mt. Gox totalled more than 6.5 billion yen ($65 million), surpassing its assets.

The exchange’s unplugging this week drew renewed regulatory attention to a currency created in 2009 as a way to make transactions across borders without third parties such as banks.