Unfortunately for New Oriental Education and Technology Group (NYSE: EDU) and its shareholders, the largest private after school test-preparation service provider in China, it has now been dragged into the muddy waters as well. The research firm struck again, this time with a 96-page report on EDU on July 18, with a "Strong Sell" rating. The report succeeded in stirring up panic over EDU, and the stock plunged 37%. It's safe to assume that Muddy Waters released their research to clients after the market closed on Jul. 16, as the stock dropped 32% overnight.