The efficient set Theorem The feasible set The feasible set is also called for the opportunity set, which represents all portfolios that could be formed from a group ofn securities. All possible portfolios that could be formed fromn securities lie either on or within the boundary of the feasible set, which has a umbrella-type shape.The Efficient Set Theorem • The feasible set – The feasible set is also called for the opportunity set, which represents all portfolios that could be formed from a group of N securities. – All possible portfolios that could be formed from N securities lie either on or within the boundary of the feasible set, which has a umbrella-type shape