As explained earlier in this chapter, there are bullet, callable, putable, and sinking fund structures. Structural analysis is simply analyzing the performance of the different structures discussed throughout this chapter. While evaluating bond structures was extremely important in the 1980s, it became less influential in credit bond market since the mid-1990s for several reasons. First, the European credit bond market almost exclusively features intermediate bullets. Second, as can be seen in Exhibit 5, the U.S. credit and the global bond markets have moved to embrace this structurally homogeneous European bullet standard. Plenty of structural diversity still resides within the U.S. high yield and EMG debt markets, but portfolio decisions in these speculative-grade sectors understandably hinge more on pure credit differentiation than the structural diversity of the issue-choice set.