As their name suggests, commercial mortgage-backed securities (CMBS) are closely related to the more popular Residential Mortgage-Backed Securities. Naturally enough, CMBS are mortgage-backed securities that are backed by commercial mortgages. In practice, CMBS tend to be less straightforward than RMBS in part because RMBS tend to be based on large numbers of almost identical mortgages that behave in a very predictable way. CMBS tend to be based on less homogenous...