A protest results in a stop work order from the company's largest client.On a generally good Monday for the stock market, AeroVironment (AVAV -9.68%) was a notable exception. The specialized defense company saw its share price sink by almost 10% that day, due to a work stoppage on a very lucrative arrangement between the company and the U.S. government. By contrast, the S&P 500 index, largely free of such burdens, inched 0.1% higher on the day.Drone disputeAeroVironment, which focuses on developing and manu ...