ILTB covers a broad spectrum of long-dated USD-denominated debt. The basket includes US Treasurys, government-related bonds (US and non-US), investment-grade and high-yield corporate bonds, and emerging-market bonds, allocating roughly equal stakes to corporate and government issues. The fund's broad geographic exposure includes US, developed-market, and emerging-market issuers. ILTB is a viable one-stop core building block for a long-term, broad exposure. ILTBs use of representative sampling means the fund has some minor tilts. The underlying index is rebalanced monthly. ILTB underwent index changes but essentially retained its exposure. From Oct. 23-Jun. 2, 2014 the fund tracked the Bloomberg Barclays U.S. Long Government/Credit Bond Index. Prior to Oct. 22, 2012, it tracked the ICE BofAML 10+Year US Corporate & Government Index.