In a seminal article on portfolio theory, Markowitz (1952) illustrated that investors are not compensated for taking on firm-specific or idiosyncratic risk; however, they are paid for taking market or systemic risk. Use your understanding of the Capital Asset Pricing Model (CAPM), statistical concepts such as standard deviation and variance, and our ideas about market efficiency and indicate whether you believe this is a good theory. Include at least two citations that support your response.