Vanguard Bond Index Funds (the Fund), formerly Vanguard Long-Term Bond ETF, seeks to track the performance of a market-weighted bond index with a long-term, dollar-weighted average maturity. It employs a passive management or indexing strategy designed to track the performance of the Barclays Capital U.S.Long Government/Credit Bond Index (the Index). The Index includes all medium and larger issues of the United States Government, investment-grade corporate, and investment-grade international dollar-denominated bonds that have maturities of greater than 10 years and are publicly issued. The Fund invests by sampling the Index, meaning that it holds a range of securities that, in the aggregate, approximates the full Index in terms of key risk factors and other characteristics. All of the Fund's investments will be selected through the sampling process, and at least 80% of its assets will be invested in bonds held in the Index. The Fund's investment advisor is The Vanguard Group, Inc.