An additional concern is that many of the transactions suffering from this risk may have been entered into for portfolio management reasons (such as the pension fund example) or regulatory capital relief and other “window dressing” purposes rather than genuinely to protect against default. Net exposure numbers quoted on earnings calls, or stress losses reported to regulators, can all be made to look more palatable if the insurance is apparently in place, while the true risks in the event of default may not have changed much. These issues raise general questions for market structure with tradeoffs that are far from trivial. Is it beneficial for, say, banks to lay off sovereign risk with other banks and other leveraged financial institutions such as hedge funds, or does the ensuing web of contingent exposures across leveraged institutions increase the systemic risks? It seems that many of these arrangements increase diversification in the case of small and medium size stress scenarios, but may actually exacerbate the systemic implications in the case of very large shocks7. These arrangements also highlight the delicacy of the appropriate regulatory structure. In many instances, subject to sufficient diversification, these tail risks might be better borne by so-called “real money” investors, i.e. insurance companies, pension funds and traditional long-only bond and equity funds, as these investor categories operate with little or no leverage.
The key difference from SIVs was that the underlying assets were largely purchased from third-parties and not necessarily in securities form. 6  BIS central bankers’ speeches  We now want to turn to an example of a structure that did at least partially survive the crisis: UK RMBS master trusts. These are versatile structures that allow an issuer to transform a portfolio of assets into a very different investment product. In principle, the master trust purchases mortgages from the bank and issues tailored bullet-maturity securities. The assets and the liabilities can be very different, e.g. the demand for the securities may be stronger in US dollars than in sterling, so an FX swap converts the cash-flows into dollars. Or most of the mortgages may be floating rate, whereas investor demand is stronger for fixed-rate product, and an interest rate swap(s) converts the cash flows accordingly. Mortgages typically pay down somewhat randomly and relatively quickly, whereas investors prefer straight-bullet maturities. The master trust can accommodate this by allowing on-going reinvestments of the pay downs and conversely allowing the trust to put assets back to the bank if the cash-flows are not sufficient to make a particular principal repayment. The downside is clearly that the on-going linkages between the issuer and the trust remain very strong, and it is thus hard to identify where economic risks ultimately reside. RMBS master trust securitisations are designed to be called on their bullet maturity date and that is how they were priced and traded.