The fund follows an index of US corporate investment grade bonds that have higher ESG ratings (based on MSCI ESG ratings) relative to their peers, and a term to maturity greater than one year. The index screens issuers from the Bloomberg US Corporate Index (parent index), including securities with ESG ratings of BBB or above. The index excludes companies that earn a significant portion of revenues from tobacco, adult entertainment, alcohol, gambling, conventional weapons and civilian firearms, any controversial weapons, significant generation of nuclear power, unconventional oil and gas, and other controversial companies. Eligible securities are then market-value-weighted within the portfolio and rebalanced on a monthly basis.