This paper introduces collateral rehypothecation, a widespread practice in derivatives, swaps, and repo markets, in a general equilibrium model with default. Rehypothecation frees up collateral because it allows lenders to resell or repledge assets pledged by borrowers. The risk that lenders will not return the asset, however, limits gains from rehypothecation. Still, when markets are contractually incomplete or decentralized, rehypothecation can achieve a superior use of scarce collateral. These results have implications for the repo market and suggest that limits to rehypothecation can cause price fragmentation.

This paper proposes a theory of excess price fluctuations in over‐the‐counter secondary markets. When heterogeneous assets trade under asymmetric information, a quality effect emerges: high liquidity lowers the quality of the pool of sellers and decreases future liquidity. Cyclical equilibria can arise even without fundamental shocks. In a cycle, investors speculate by bidding up the price of low‐quality assets, anticipating a high resale price at the peak. When this resale effect is strong, cycles disappear and multiple steady states coexist with different levels of liquidity. The model rationalizes empirical patterns for corporate bonds and housing in particular.