Somebody just bought a whole heck of a lot of bitcoins.

Last week, the U.S Marshals' Service auctioned off 29,656.5 bitcoins it had seized from the Silk Road, the online illicit drug marketplace the feds shutdown this past fall, and on Tuesday, the service said it has moved all those bitcoins—the equivalent of about $19 million—into the wallet of the lucky auction winner. Lynzey Donahue, a spokeswoman for the service confirmed that the entire stash of seized bitcoins went to a single bidder, but she wouldn't say who that was—or how much they paid for the bitcoins. Speculation in the bitcoin community is that they went for pretty close to market value. That's about $640 today.

Bitcoin is the world's most popular digital currency—a new type of money that can significantly change the way we pay for things and transfer funds from place to place—and the Marshals' auction generated a lot of interest. The service sold the bitcoins in 10 lots of about 3,000 bitcoins each, and Donahue says that there were a total of 63 bids made by 45 bidders. Bidders put in their bids on Friday, and they were notified about whether they won or not on Monday.

>The auction caused some anxiety in the bitcoin markets, where a one-off purchase of several thousand bitcoins could move the price by more than $100.

The auction caused some anxiety in the bitcoin markets, where a one-off purchase of several thousand bitcoins could move the price by more than $100, according to current order books. The big worry was that someone would snatch up the bitcoins for a song and then sell them, depressing the market. There are just under 13 million1

bitcoins in circulation, putting the total market cap of the emerging digital currency at around $8.3 billion. And another auction could be on the way. The feds have also have second stash of 144,342 bitcoin, seized from Ross Ulbricht, the Silk Road's alleged mastermind.

While it's not clear who bought the Silk Road bitcoins, there are a few well-funded startups that could use a large stash of the digital currency. These are startups in the business of helping people and companies set up bitcoin services that let them store, send, and receive the digital currency. They need large amounts of bitcoins so that they can sell them to users—and protect their own position in the currency, whose value can fluctuate. One of these companies, Coinbase, says it did not win the auction. A well-funded Coinbase competitor, Circle, didn't have a comment on the auction.

The money may also have gone to individual or institutional investors who lined up to participate in the auction. The Marshal's Service accidentally leaked out a list of the auction's potential participants a few weeks back.

Update 7/2/14: We now know who won the auction: VC Tim Draper. Find out what he's going to do with them here.

1Correction 10:09 EST 07/02/14: An earlier version of this story incorrectly stated the total number of bitcoins in circulation.