NBER Working Papers by Adi Sunderam

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Working Papers

September 2015Gradualism in Monetary Policy: A Time-Consistency Problem?
with Jeremy C. Stein: w21569
We develop a model of monetary policy with two key features: (i) the central bank has private information about its long-run target for the policy rate; and (ii) the central bank is averse to bond-market volatility. In this setting, discretionary monetary policy is gradualist, or inertial, in the sense that the central bank only adjusts the policy rate slowly in response to changes in its privately-observed target. Such gradualism reflects an attempt to not spook the bond market. However, this effort ends up being thwarted in equilibrium, as long-term rates rationally react more to a given move in short rates when the central bank moves more gradually. The same desire to mitigate bond-market volatility can lead the central bank to lower short rates sharply when publicly-observed term pr...
December 2014The Rise and Fall of Demand for Securitizations
with Sergey Chernenko, Samuel G. Hanson: w20777
Collateralized debt obligations (CDOs) and private-label mortgage-backed securities (MBS) backed by nonprime loans played a central role in the recent financial crisis. Little is known, however, about the underlying forces that drove investor demand for these securitizations. Using micro-data on insurers’ and mutual funds’ bond holdings, we find considerable heterogeneity in investor demand for securitizations in the pre-crisis period. We argue that both investor beliefs and incentives help to explain this variation in demand. By contrast, our data paints a more uniform picture of investor behavior in the crisis. Consistent with theories of optimal liquidation, investors largely traded in more liquid securities such as government-guaranteed MBS to meet their liquidity needs during the cris...
June 2013Concentration in Mortgage Lending, Refinancing Activity and Mortgage Rates
with David S. Scharfstein: w19156
We present evidence that high concentration in local mortgage lending reduces the sensitivity of mortgage rates and refinancing activity to mortgage-backed security (MBS) yields. A decrease in MBS yields is typically associated with greater refinancing activity and lower rates on new mortgages. However, this effect is dampened in counties with concentrated mortgage markets. We isolate the direct effect of mortgage market concentration and rule out alternative explanations based on borrower, loan, and collateral characteristics in two ways. First, we use a matching procedure to compare high- and low-concentration counties that are very similar on observable characteristics and find similar results. Second, we examine counties where concentration in mortgage lending is increased by bank merg...
February 2009Inflation Bets or Deflation Hedges? The Changing Risks of Nominal Bonds
with John Y. Campbell, Luis M. Viceira: w14701
The covariance between US Treasury bond returns and stock returns has moved considerably over time. While it was slightly positive on average in the period 1953--2009, it was unusually high in the early 1980''s and negative in the 2000''s, particularly in the downturns of 2000--02 and 2007--09. This paper specifies and estimates a model in which the nominal term structure of interest rates is driven by four state variables: the real interest rate, temporary and permanent components of expected inflation, and the ""nominal-real covariance"" of inflation and the real interest rate with the real economy. The last of these state variables enables the model to the changing covariance of bond and stock returns. Log bond yields and term premia are quadratic in these state variables, with ...

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