I’m a little confused about the concept. The CFAI text explains that an investor seeking beta for an equity index could use a fixed income manager for alpha generation and wind up with equity beta+ fixed income alpha. What confuses me is to consider using beta for the S&P which is expected to return, say, 10% with a fixed income manager for alpha that is using an index expected to return 3%. Even if he generates 2% alpha, the investor would have been better off with the pure beta play. For example, say he allocated 80% to the S&P and 20% to the FI manager, his total return would be (10%*0.8)+(5%*0.2)= 9%; where he would’ve been better off investing everything in the S&P getting a 10% return. What am I missing with this. Would futures be used or some type of leverage on the FI manager?