How to make portfolio choice How can Markowitz's approach be used to select portfolio once it is recognized that there are an infinite number of portfolio available for investment? What happens when the investor considers investing in a set of securities, one of which is riskless? What happens if the investor is allowed to buy securities on margin?How to make portfolio choice • How can Markowitz’s approach be used to select portfolio once it is recognized that there are an infinite number of portfolio available for investment? • What happens when the investor considers investing in a set of securities, one of which is riskless? • What happens if the investor is allowed to buy securities on margin?