Rather, I am interested this evening in those instruments, structures, firms or markets which, alone or in combination, and to a greater or lesser extent, replicate the core features of commercial banks: liquidity services, maturity mismatch and leverage. In that spirit, I will say something about money market mutual funds; finance companies; Structured Investment Vehicles and Asset Backed Commercial Paper; and securities dealers. I will also say something about some markets. In particular, the securities lending market; but also how the RMBS/ABS market can combine with repo funding to create investment structures whose leverage and liquidity risk creates some of the brittleness of banking systems. It is not intended to be an exhaustive, systematic survey. And beyond those interested in the details of how markets work, it is the general message that matters. Because some common threads are clear. Notably, maturity and credit transformation. Each of the vehicles, instruments or markets I will discuss has been used to transform longer-maturity, less liquid assets (loans) into shorter maturity, more liquid liabilities. In each case we need to decide whether or not we want to set constraints around the operation of those forms of shadow banking. And we need some principles to guide us when, inevitably, we confront new variants of shadow banking in the future. I do not have all the answers to these questions, so my goal this evening is to push them up the agenda. As the Governor of the Bank has underlined, it is vital we debate the structure of the financial system.
So we need policies and principles that stand in the way of its weakening the resilience of the system, while allowing enterprise and our capital markets to flourish. 15  See the Bank’s recently published paper: “The role of macroprudential policy: A discussion paper” and Tucker P M W (2009e), “The debate on financial system resilience: Macroprudential instruments” at the Barclays Annual Lecture in London. 8  BIS Review 6/2010