In the event that investors do not understand that banks are in trouble and that the global economy faces a deep recession, Alan Greenspan has written it all out. The former Fed boss is good enough to explain the obvious as his primary thesis: "The insolvency crisis will come to an end only as home prices in the US begin to stabilise and clarify the level of equity in homes, the ultimate collateral support for much of the financial world’s mortgage-backed securities." The balance of the self-satisfied essay is at FT.com.