Vanguard Bond Index Funds - Vanguard Long-Term Bond ETF is an exchange traded fund launched and managed by The Vanguard Group, Inc. The fund invests in the fixed income markets of the United States. It invests in investment grade securities including government securities, corporate and international dollar-denominated bonds that have maturities of greater than 10 years that are rated BBB- or above by S&P. It seeks to replicate the performance of the Bloomberg U.S.