Reaching for Duration and Leverage in the Treasury Market.

We show substantial variation in mutual funds' use of Treasury futures, both over time and across funds. This variation from mutual funds drives much of the time series variation in aggregate Treasury futures open interest, including over 60% of the recent rise in Treasury futures positions. We provide evidence these Treasury futures positions are largely attributable to mutual funds "reaching for duration" in order to track the duration of a benchmark index with high cash Treasury exposure. Specifically, we show mutual funds use futures to fill the gap between their portfolio and the index that results when they tilt their cash positions toward higher return but lower duration assets, such as mortgage-backed securities and equities, and away from cash Treasuries. Treasury futures positions are more common in mutual funds which indicate a focus on dual objectives of duration management and total return whose style has a higher allocation to Treasuries. Reaching for duration allows funds to track their index better at lower cost, but increases leverage in the Treasury market both through mutual funds long Treasury futures positions and through the leverage of hedge funds who take the corresponding short positions in Treasury futures. [ABSTRACT FROM AUTHOR]