The price of Bitcoin on Bitstamp crashed by 18% from $7,600 to $6,250 from 2:58am UTC to 3:09am UTC; in just 11 minutes. Bitstamp is one of the two exchanges that is used to determine the index price of Bitcoin on BitMEX, along with Coinbase. As a result, as the price crashed on Bitstamp, $250 million of long positions was liquidated on BitMEX, which further pushed down price on other exchanges.
Bistamp said that "a large sell order was executed on our BTC/USD pair today, strongly impacting the order book" and reiterated that the system behaved as designed "processing and fulfilling the client’s order as it was received." Moreover, Bitstamp said that it closely examines every event that causes large-scale movement in its order book.