Critically analyze the three main assumptions of the Capital Asset Pricing Model (CAPM) and why is the market portfolio efficient according to CAPM.

Your critical response should have a minimum of two sources published in the last 12 months which should be used to support the content within the postings, proper in-text citations. Your responses should be professionally written and correctly formatted references should be prepared consistent with the APA. The list of references should be physically positioned at the end of the postings.