Successive spasms of legislative and regulatory actions followed the financial crisis of 2007-8 — accompanied by a chorus of assertions that these and more changes are needed to avert future crises.

To judge from the substance of the new laws and regulations, one might imagine that the crisis was caused by a whole host of exotic bank oversteps, such as arbitrary increases in credit card rates; banks buying and selling securities for their own accounts; and overdraft fees on debit cards. But although the purported cures to eliminate these supposed causes are doubtless less painful than another crisis would be, fact is that none of these putative forms of misconduct by banks caused or even contributed to the crisis.

Put forward more seriously at times is the notion that subprime consumer lending somehow ran amok. That's also wrong. Payday lenders didn't go broke. Subprime auto lenders remained in business. Pawnshops are flourishing.

The catastrophe started and will finish with residential mortgages. And it was by no means limited to "subprime mortgages" — unless we now expand our use of the term subprime to include poorly designed and underwritten mortgages that were marketed to people with high credit scores. Fannie Mae and Freddie Mac exhausted their capital primarily because of their guarantees of so-called conforming mortgages, not subprime mortgages.

Why were unsound products, such as payment option and 100% mortgages, so heavily marketed? Why were mortgages offered to consumers who failed to meet reasonable underwriting standards such as verification of income? During the same period, banks and non banks maintained a full range of other sane and profitable lending products, from boat loans to deposit advances. None of these suffered fulminating losses. What was different about mortgages?

Mortgages and no other type of consumer loan made possible securitizations in which, once the loans were sold, any perceived risk to the originating and pipeline institutions was tiny compared with their profits from the securitization activity. You couldn't do the same thing with auto loans or credit cards. When a credit card securitization fails because of high credit losses — a very rare event — the lender either makes good or is bankrupted.

If you expect to make money originating a mortgage irrespective of its ultimate performance, then you minimize origination time and cost — and quality. This is most obvious to a mortgage broker or correspondent bank. But it applies also to anyone who can profit by selling the mortgage into an impersonal and heedless market.

The evidence from other consumer lending lines of business tells us that without the pull exerted by the immensely profitable and seemingly riskless securitization business, the competitive cheapening of mortgage risk — led by Countrywide as it endlessly sought to expand its market share to and above 30% — could not have occurred.

In an odd variant of Gresham's law (bad money drives out good), the distributors of mortgage securities created so much demand for them, inattentive to underlying quality, that lenders no longer saw any benefit in controlling credit risk. To a considerable extent, bad mortgages drove out good.

What participants had not foreseen was that when the music stopped, many of them would be poisoned by the toxic assets that they held in the pipeline or had ready for sale. They are also subject to later punishment for violating securitization terms, and will continue to be required to take more mortgages back, or pay compensation for them. These exposures are very large compared with any perception of risk that is likely to be created by proposed rules requiring originators to retain 5% or 10% of what they sell.

No matter. In the short to medium term, we can be sure that the mythical small Norwegian town will not again be buying any weird American mortgage paper on the strength of its ratings. It's unlikely these memories will dim even within a generation. So, we too are safe for that period from a repeat. But, are there broader or deeper frailties in the system and its regulation?

Yes indeed. Auction-rate securities are an instructive example. Benefiting from their special regulatory status, banks elicited the issuance of new forms of debt that were not understood by many to whom they were sold and which could become illiquid, unsalable. The scale here was far smaller than for mortgages, but put-back liabilities resulted from banks' sale of these securities also. How do we guard against the next clever idea? The challenge is large.

There was a time when banks could print money. This turned out to be a bad practice. It was abused. Maybe insured depository institutions and their affiliates should not be allowed to participate in (or sell assets into) public issuance of any debt security not explicitly protected by their own credit.

Subscribe Now

Access to authoritative analysis and perspective and our data-driven report series.

14-Day Free Trial

No credit card required. Complete access to articles, breaking news and industry data.