From abstract:<p>"We identify and analyze the impact of suspicious trading activity (STA) on the
Mt. Gox Bitcoin currency exchange between February and November 2013. We discuss
two distinct STA periods in which approximately 600,000 bitcoins (BTC) valued at
$188 million were acquired by agents who did not pay for the bitcoins. During the
second period, the USD-BTC exchange rate rose by an average of $20 at Mt. Gox on
days when suspicious trades took place, compared to a slight decline on days without
suspicious activity. Based on rigorous analysis with extensive robustness checks, we
conclude that the suspicious trading activity caused the unprecedented spike in the
USD-BTC exchange rate in late 2013, when the rate jumped from around $150 to
more than $1,000 in two months."