Michael Kors (KORS) slumped 6% on Aug. 4 in massive volume despite reporting another strong quarter of double-digit profit and sales growth. The culprit? Worries about the company’s profit margins. Why are profit margins so key? They measure how much a company actually makes out of every dollar in sales. It’s displayed as a percentage. For instance: If a company has a 22% profit margin, then it nets 22 cents per dollar of sales.