The pricing of subprime mortgage risk in good times and bad: evidence from the ABX.HE indices

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Abstract
This article investigates the pricing of subprime mortgage risk using data for the ABX.HE indices, which have become a key barometer of market conditions during the recent financial crisis. After a discussion of ABX index mechanics and observed pricing patterns, we use regression analysis to establish the relationship between observed index returns and macroeconomic news as well as market-based proxies of various pricing factors. The results imply that declining risk appetite and heightened concerns about market illiquidity–likely due in part to significant short positioning–have provided a sizeable contribution to the observed collapse in ABX prices. In particular, while fundamental factors, such as housing market activity, have continued to exert an important influence on the subordinated indices, those backed by senior exposures have tended to react more to the general deterioration of the financial market environment. This provides further support for the inappropriateness of pricing models that do not account sufficiently for factors such as risk appetite and liquidity risk, particularly in periods of stress. In addition, as related risk premia can be captured by unconstrained investors, these findings lend support to government measures aimed at taking troubled assets off banks’ balance sheets (e.g. the Troubled Asset Relief Program).