After announcing the launch of a secondary offering and updating guidance, Acacia Communications (ACIA) ended up over 11% on Wednesday. The chart though shows a stock topping as insiders dump nearly 4 million shares in total while the company generates blowout quarterly numbers. The key concern for anybody buying the stock now is that Matrix Partners is unloading 1.8 million shares while still controlling 10.3 million shares or 29% of the outstanding stock. Do you really want to buy Acacia as these insiders are selling with a chart like that?Disclosure: No position