Wait -- Bitcoin's price roller coaster doesn't reflect the efficient market hypothesis?... Also see Bitcoin’s Collapse Accelerates, Falls to Lowest Since February (Bloomberg)
"Many industry players expressed concern at the time that the prices were being pushed up at least partly by activity at Bitfinex, one of the largest and least regulated exchanges in the industry. The exchange, which is registered in the Caribbean with offices in Asia, was subpoenaed by American regulators shortly after articles about the concerns appeared in The New York Times and other publications.Bitcoin’s Price Was Artificially Inflated Last Year, Researchers Say -- NYT
Mr. Griffin looked at the flow of digital tokens going in and out of Bitfinex and identified several distinct patterns that suggest that someone or some people at the exchange successfully worked to push up prices when they sagged at other exchanges. To do that, the person or people used a secondary virtual currency, known as Tether, which was created and sold by the owners of Bitfinex, to buy up those other cryptocurrencies."