PrefBlog

The Bank for International Settlements has announced the release of Working Paper #279, The pricing of subprime mortgage risk in good times and bad: evidence from the ABX.HE indices by Ingo Fender and Martin Scheicher.

This paper investigates the market pricing of subprime mortgage risk on the basis of data for the ABX.HE family of indices, which have become a key barometer of mortgage market conditions during the recent financial crisis. After an introduction into ABX index mechanics and a discussion of historical pricing patterns, we use regression analysis to establish the relationship between observed index returns and macroeconomic news as well as market-based proxies of default risk, interest rates, liquidity and risk appetite. The results imply that declining risk appetite and heightened concerns about market illiquidity—likely due in part to significant short positioning activity—have provided a sizeable contribution to the observed collapse in ABX prices since the summer of 2007. In particular, while fundamental factors, such as indicators of housing market activity, have continued to exert an important influence on the subordinated ABX indices, those backed by AA and AAA 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 sufficiently account for factors such as risk appetite and liquidity risk, particularly in periods of heightened market pressure. In addition, as related risk premia can be captured by unconstrained investors, ABX pricing patterns appear to lend support to government measures aimed at taking troubled assets off banks’ balance sheets—such as the US Troubled Asset Relief Program (TARP).

The authors observe:

With market liquidity vanishing and entire market segments becoming largely dysfunctional, factors other than credit risk became increasingly important drivers of observed prices. This, in turn, rekindled earlier doubts concerning the validity of currently available models for the pricing of credit risk, particularly for portfolio instruments such as mortgage-backed securities and other complex securitisations.

The results presented in this paper suggest that declining risk appetite and heightened concerns about market illiquidity have provided a sizeable contribution to the observed collapse in ABX prices since July 2007. While fundamental factors, such as indicators of housing market activity, have continued to exert an important influence on the subordinated ABX indices, the AA and AAA indices have tended to react more to the general deterioration of the financial market environment, such as declining risk appetite and market liquidity. These results underline the well-established view that risk premia are important components of observed prices for default-risky products, and that the relative importance of non-default risk factors will tend to increase in periods of strong repricing of credit risk. This suggests that theoretical pricing models that do not sufficiently account for these factors may be inappropriate, particularly in periods of heightened market pressure.

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