iPath US Treasury Flattener ETN (FLAT) is an exchange-traded note issued by Barclays Bank PLC that provides inverse exposure to the performance of the Barclays US Treasury 2Y/10Y Yield Curve Index. The ETN employs long positions in derivatives such as futures contracts on 2-year U.S. Treasury notes and short positions in derivatives such as futures contracts on 10-year U.S. Treasury notes, targeting investors seeking to benefit from a flattening U.S. Treasury yield curve in the fixed income markets of the United States. Launched on August 9, 2010, and domiciled in the United Kingdom with Barclays Bank PLC headquartered in London, the product trades on the NASDAQ exchange under the ticker FLAT and focuses on U.S. Treasury spread strategies without subsidiaries or parent company relationships beyond its issuer. In a significant operational change, Barclays announced the redemption of multiple iPath ETNs in June 2025, including series that align with FLAT's characteristics, exercising its issuer call option to redeem outstanding notes in full following cash tender offers and consent solicitations that amended indentures for early redemption. As of late 2025, trading activity remains minimal with low volume and the product listed as no longer active on certain platforms, reflecting Barclays' ongoing portfolio rationalization of legacy iPath ETNs.