Lehman Brothers Aggregate Bond Index includes fixed-rate debt issues rated investment grade or higher by Moody's Investors Service, Standard and Poor's®, or Fitch Investor's Service, in that order. (It also includes commercial mortgage-backed securities.) Bonds or securities included must be fixed rate, must be dollar-denominated and nonconvertible, and must be publicly issued. Bonds included span the maturity horizon, although all issues must have at least one year to maturity. All returns are marketvalue weighted inclusive of accrued interest.