Rumors about the possible collapse of Mt. Gox are sending shock waves through the community that has embraced the virtual currency.
The Bitcoins apparently lost by Mt. Gox account for about 6 percent of all Bitcoins in circulation. If they are lost, it's unclear who may control them.
The uncertainty surrounding Mt. Gox comes just as a New York firm, SecondMarket, was announcing plans to create a new exchange with some major banks as possible partners.
Without the trouble at Mt. Gox, the SecondMarket plans would have been seen as a major boon for virtual currencies, providing a potential entry point into the Bitcoin market for large banks, which have so far avoided virtual currencies as their price has skyrocketed.
Barry Silbert, SecondMarket's chief executive, said that he had already talked with several banks and financial companies about joining the new exchange, along with financial regulators, and that he hoped to have it in operation this summer.
But the apparent collapse of Mt. Gox could shake the faith of early Bitcoin adopters. Ryan Galt, a blogger who writes frequently about Bitcoin and was one of the first to circulate the news about Mt. Gox, wrote Monday: "I do believe that this is one of the existential threats to Bitcoin that many have feared and have personally sold all of my Bitcoin holdings."