The current state of affairs feels different from 2008, when the crash was caused by the overexposure of banks to the US housing market, and turbocharged by the widespread use of new financial instruments that were supposed to reduce risk but did the opposite.
Everyone in financial markets knows you cannot reduce risk. You can, however, slice and dice it and spread it. Thereby reducing the risk to any one specific position or market participant. That also means that you can concentrate risk in a position to to a particular market participant which may or may not be one of those grand ideas.
Those mortgage pools with the income streams sliced and diced by risk. Worked exactly as they were supposed to. The risk of non-patyment was concentrated into those C tranches – the “equity” tranches. The AAA tranches were supposed to be credit risk free. Because the C, then B., then A etc tranches would all have to go bust first.
This all worked exactly as planned. The C tranches all did fall over. The AAA tranches kept paying out and some of them are even still doing so – tho’ getting to be pretty small now as repayments/remortgages happen.
Risk was spread – that’s why German banks went bust when American mortgages soured – they’d bought C tranches perhaps. You know, spreading that risk?
There was also concentration. No rational bugger wanted to buy thsoe C tranches but given the risk they paid higher rates than it cost to finance them with wholesale money on a bank balance sheet. So, banks loaded up with them. Vast, vast, piles teetering on tiny capital bases. So, when they all went bust – both dispersion and concentration of risk, see – then the banks were, umm, in serious trouble.
Everyone agrees you cannot reduce risk. But you can allocate it. The error was in who piled in to carry that risk, not the slicing and dicing of it. If those C tranches had been in hedge funds, backed by proper capital bases, no GFC. Of course, hedge funds weren’t stupid enough to take that risk but that’s another matter.