VTC, as a fund-of-funds, taps the liquidity and scale of three existing Vanguard ETFs of investment-grade US corporates: VCSH for short-term, VCIT for intermediate, and VCLT for long-term maturities. As a result, the fund is able provide a diversified exposure to the market across the broad spectrum within one ticker. The fund uses a sampling method in tracking its index, which means it will invest in a sample of securities that collectively have an investment profile similar to that of the underlying index. The index is rebalanced monthly.