1)Mark used the techniques of quadratic programming to identify the efficient portfolio

2)Using the expected return and risk of each security under consideration and the covariance estimates for each pair of securities, he calculated risk and return for all possible portfolios

3)Then for any specific value of expected portfolio return, he determined the least risk portfolio using quadratic prog.

4)With another value of expected portfolio return, a similar procedure again give the minimum risk portfolio.

5)The the process is repeated with different values of expected return, the resulting minimum risk portfolios constitute the set of efficient portfolios.