With risk-averse arbitrageurs and an effective lower bound (ELB) on nominal rates, nonlinear interactions among short-rate expectations, bond supply, and term premia emerge in equilibrium. These interactions, which are absent from affine models, help explain the observed behavior of the yield curve near the ELB, including evidence about unconventional monetary policy. The impact of both short-rate expectations and bond supply are attenuated at the ELB. However, in simulations of the post-crisis experience in the U.S., shocks to investors’ duration-risk exposures have much smaller effects than shocks to the anticipated path of short rates. The latter shocks matter, in part, because of the reduction in interest-rate volatility associated with a longer expected stay at the ELB—a novel channel of unconventional policy.

The Federal Reserve’s 2009 program to purchase $300 billion of US Treasury securities represented an unprecedented intervention in the Treasury market and provides a natural experiment with the potential to shed light on the price elasticities of Treasuries and theories of supply effects in the term structure. Using security-level data on Treasury prices and quantities during the course of this program, we document a ‘local supply’ effect in the yield curve—yields within a particular maturity sector responded more to changes in the amounts outstanding in that sector than to similar changes in other sectors. We find that this phenomenon was responsible for a persistent downward shift in yields averaging about 30 basis points over the course of the program (the “stock effect”). In addition, except at very long maturities, purchase operations caused an average decline in yields in the sector purchased of 3.5 basis points on the days when those operations occurred (the “flow effect”). The sensitivity of our results to security characteristics generally supports a view of segmentation or imperfect substitution within the Treasury market during this time.