On the People's Bank of Chinas behest, the four major Chinese bitcoin exchanges introduced trading fees this week, causing a significant drop in volume. While the exchanges have been charging for withdrawals, a tiered fee structure incentivised traders to maximize their volume in any way possible. Traders have long since suspected Chinese exchange volume to be manipulated through things such as wash trading and volumizing.
http://bravenewcoin.com/news/bitcoin-price-analysis-pboc-crushes-volume/