Constant Maturity Mortgage

In the United States secondary mortgage market, the Constant Maturity Mortgage (CMM) rate is a financial index representing the theoretical yield of a par value agency residential mortgage-backed security (agency RMBS). Unlike the constant-maturity treasury (CMT) which reflects government borrowing costs, the CMM reflects the yield required by investors to transact agency RMBS (such as those issued by Fannie Mae or Freddie Mac) at a price of 100.

Source: Wikipedia — Constant Maturity Mortgage (CC BY-SA 4.0)