first, it started with a piece of research saying one should buy the close/after hours and sell at the open the next day. One should have done excatly the opposite. futures were systematically pushed lower after hours to suck in intraday short sellers during european hours. 2 hours into european open, futures would start rising and these intraday traders would need to buy back. They were decimated. Then it was it the quant's turn. Because we all know what the signals are for the quant models, it was very easy to inflict them maximum pain by buying what they would short and selling what they would buy. When you have unlimited ammo, it's a no brainer. At the time quants funds had no inflows, they couldn't fight. Quant funds lost 20% in April. Now, it's the turn of CTAs. We've reached a point where MAs are crossing and long term trend CTAs have started reversing. All these long term CTAs were short index futures, it's buyback time. How did they do it? unlimited ammo, crashing the vix, ETF "hedging",... Very very well planned and perfectly executed. A lesson in market manipulation. What next guys?