We study an important recent series of buyback auctions conducted by the U.S. Treasury in retiring $67.5 billion of its illiquid off-the-run debt. The Treasury was successful in buying back large amounts of illiquid debt while suffering only a small market-impact cost. The Treasury included the...

I develop an interest rate model with separate factors driving innovations in bond yields and their covariances. It features a flexible and tractable affine structure for bond covariances. Maximum likelihood estimation of the model with panel data on swaptions and discount bonds implies pricing...