SBND tracks an index comprised of six sub-indices from different segments in the fixed income space. The index assigns each of the sub-indices their fixed weight within the fund: mainly, 10% in US mortgaged-backed securities, 10% in asset-backed securities, specifically, automobile bonds, 10% in non-agency backed securities, 30% in US corporate investment grade bonds, 20% in US corporate high-yield bonds, and 20% in emerging markets sovereign and quasi-sovereign debt. Each security within each sub-index is market-value weighted and is selected using maturity, credit rating and market value requirements. The index expects an overall portfolio duration that will not exceed 3.5 years. Rebalancing and reconstitution is done on a monthly basis.
