Overstock (OSTK) CEO Patrick Byrne is a pioneer in bitcoin. But even he is having trouble pinpointing the reason behind bitcoin's plunge on Friday.

"Well, I don't know if it's a flash crash, a trading issue or the new ability of Wall Street to short," Byrne told TheStreet when asked about the mysterious drop.

It's almost useless to quote a price on bitcoin as the swings have been that severe -- and swift -- on Friday. Bitcoin prices have crashed 12% inside a day to $12908. Since Sunday, prices are down 32%.

Byrne knows a thing or two about bitcoin. Overstock was the first retailer to start accepting the crypto as payment in 2014. On Monday, Byrne debuted a $250 million initial coin offering (ICO) for a new trading platform known as tZero. Byrne, who founded Overstock in the late 1990s, has also reportedly started to shop the company so he could focus all his attention on advancing blockchain technology. 

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