Collateral Unchained: Rehypothecation Networks, Concentration and Systemic Effects
SCIENCES PO OFCE WORKING PAPER n° 07, 2018/01/31
39 Pages Posted: 23 Feb 2018
Date Written: January 31, 2018
We study how network structure affects the dynamics of collateral in presence of rehypothecation. We build a simple model wherein banks interact via chains of repo contracts and use their proprietary collateral or re-use the collateral obtained by other banks via reverse repos. In this framework, we show that total collateral volume and its velocity are affected by characteristics of the network like the length of rehypothecation chains, the presence or not of chains having a cyclic structure, the direction of collateral flows, the density of the network. In addition, we show that structures where collateral flows are concentrated among few nodes (like in core-periphery networks) allow large increases in collateral volumes already with small network density. Furthermore, we introduce in the model collateral hoarding rates determined according to a Value-at-Risk (VaR) criterion, and we then study the emergence of collateral hoarding cascades in different networks. Our results highlight that network structures with highly concentrated collateral flows are also more exposed to large collateral hoarding cascades following local shocks. These networks are therefore characterized by a trade-off between liquidity and systemic risk.
Keywords: Rehypothecation, Collateral, Repo Contracts, Networks, Liquidity, Collateral- Hoarding Effects, Systemic Risk.
JEL Classification: G01, G11, G32, G33
Suggested Citation: Suggested Citation