There are a slew of metrics that go into the calculation of performance incentives for Fannie Mae, Freddie Mac and their top executives. Some of them – like hitting softball market share targets when the only competition is Ginnie Mae and Freddie Mac – seem hard to miss. For 2010, one of Fannie’s performance goals was to achieve a 33 percent share of new single-family mortgage-backed securities issuance. The company actually attained a 44 percent share of MBS issuance last year, which helped Fannie’s top executives earn 89 percent to 99 percent of their maximum long-term...