The iShares 20+ Year Treasury Bond ETF (TLT) is an exchange-traded fund (ETF) that tracks the performance of the ICE U.S. Treasury 20+ Year Bond Index. The fund is managed by BlackRock and was launched in 2002.

The ICE U.S. Treasury 20+ Year Bond Index is a market-capitalization-weighted index that measures the performance of U.S. Treasury bonds with maturities of 20 years or more. The index includes both on-the-run and off-the-run bonds.

TLT is a popular ETF for investors who are looking for exposure to long-term U.S. Treasury bonds. The fund has a low expense ratio.