USB is passively managed and tracks a variety of investment-grade, USD-denominated bonds issued by companies domiciled in the US, Canada, Western Europe or Japan. To be included in the index, securities must be rated BBB- or above, have an outstanding face value of at least $500 million, and have a remaining maturity of at least one year. Selected securities are sorted into five equally-weighted buckets across each year of maturity. Within each maturity bucket, the index employs a market value weighting methodology to weight individual positions. Coupon payments and redemption proceeds are reinvested as of the call date in 13-week US treasury bills until the next monthly rebalancing, where they are then invested in bonds that have a maturity of five years. On a monthly basis, the index is reviewed to ensure that the weight of each maturity bucket is within 20% of its target weight. If not, then the index is fully rebalanced.