The basic facts about the financial crisis that originated in the home mortgage market are not in dispute:

  • The housing bubble that preceded the financial crisis was reinforced by an excessive liberalization of mortgage lending terms that produced toxic mortgages — these were mortgages that could not be repaid unless house prices continued their rapid rise.
  • Each player involved in the process was able to pass on the risks associated with these mortgages to the next player in the process — until it ended up with the investor purchasing the security that was issued against the mortgages. Among all the parties involved in the process, the investor typically was the least capable of controlling or assessing the risk.

Policy remedies designed to prevent it from happening again have focused mainly on the loan origination process. The logic is simple: Prevent the origination of toxic mortgages and we prevent future crises.

This logic underlies the drastic tightening of underwriting requirements by Fannie Mae, Freddie Mac, large lenders and regulators.

But a tightening of underwriting rules after the crisis that should have been done before the crisis is not logical at all. My mailbox these days is stuffed with letters from potential borrowers with impeccable credentials who can’t get loans today because of new and ill-considered underwriting rules. Tragically, these rules are preventing large numbers of borrowers with mortgages in good standing from refinancing at today’s low rates.

A focus on the need to regulate loan originations also underlies more comprehensive reform proposals. A common argument is that every party involved in creating the mortgage — the retail lender making the loan, the wholesale lender buying it from the retail lender, and the investment bank buying it from the wholesale lender to place in a security — should be required to assume part of the risk of loss. In my view, this argument misses the point.

Requiring a lender to retain 5 percent of the risk of loss on a toxic mortgage that it originates to sell will force the lender to increase its markup by enough to cover the risk, but it won’t deter the lender from making the loan if there is a ready buyer for it.

The reason toxic mortgages were originated was that there was a secondary market for them. Without that market, there would have been no subprime or Alt-A mortgages. The skin that is needed to fix the game is that of the issuers of mortgage-backed securities (MBSs). All MBSs should be full-faith liabilities of the issuer, meaning that they assume 100 percent of the risk.

The private MBSs developed by Wall Street were all "stand-alones" — the reserves and other forms of credit enhancement on a given security were available only to investors in that security.

If not needed, the credit enhancements on a security were withdrawn, paid either to the issuer or to a third party who purchased them. They were not available to investors in another security that suffered losses that exceeded the credit enhancements available on that security.

For this reason, the private secondary market was a house of cards. High-loss rates on MBSs issued late in the bubble, which swamped their available credit enhancements, caused a cascading loss of confidence in all of them. In a relatively short period, the market ceased to function effectively.

The breakdown of the private MBS market was major factor in the unfolding crisis. Institutions holding private MBSs in their portfolios had to write down their value, which could deplete or eliminate their capital. This was a factor in the case of the five major financial institutions that either failed or were forced into government-assisted mergers in 2008: Bear Stearns, Washington Mutual, Lehman Brothers, Wachovia and Merrill Lynch.

Writedowns in the value of MBSs also had a major impact on short-term borrowing secured by MBS collateral. This created a major problem for investment banks, who were accustomed to borrowing enormous amounts overnight in this way.

As the value of the collateral became increasingly suspect, lenders kept asking for more and more collateral. The failure of Bear Stearns and Lehman Brothers was due not only to the depletion of their capital, but also to their inability to post enough acceptable collateral to secure their overnight borrowings.

Contrast our experience with that of Denmark. They had a housing bubble much like ours, and all the mortgages written in Denmark are placed in securities issued by private mortgage banks, but not one security went into default. During the worst part of the crisis in 2008, when the private MBS market in the U.S. was shut down, it was business as usual in Denmark. Why the difference?

Where private MBSs in the U.S. are stand-alones, mortgage bonds in Denmark are full-faith liabilities of the mortgage banks issuing them. This means that if the default rate on the mortgages underlying one of the bonds issued by a bank turned out to be unusually high, investors in that bond would be protected by all the resources of the issuing bank.

There has never been a default on a Danish mortgage bond in more than 200 years.

Loan originators did a lot of nasty things during the housing bubble, but that should not blind us to the root source of the problem, which is the private MBS market. Making loan originators assume 5 percent of the risk on the loans they sell would not bolster that market at all, though it would create enormous record-keeping problems.

What is needed to prevent the creation of another house of cards is a requirement that issuers of MBSs accept 100 percent of the risk. Then an MBS will fail only if the issuer fails, which in Denmark has never happened, but if it did happen, MBSs issued by other firms probably would not be affected.

Note: The Senate’s Proposed Restoring American Financial Stability Act of 2010 would require security issuers to retain 5 percent of the credit risk on the security, or less than 5 percent by the amount of risk retained by the originator selling the loan to the issuer. The 5 percent requirement could also be reduced if the loans had "reduced credit risk." This reads like it was written by investment banks.

The writer is professor of finance emeritus at the Wharton School of the University of Pennsylvania. Comments and questions can be left at


What’s your opinion? Leave your comments below or send a letter to the editor. To contact the writer, click the byline at the top of the story.

Show Comments Hide Comments


Sign up for Inman’s Morning Headlines
What you need to know to start your day with all the latest industry developments
By submitting your email address, you agree to receive marketing emails from Inman.
Thank you for subscribing to Morning Headlines.
Back to top
Inman Connect is LIVE today! Join us and thousands of your peers from wherever you are.Register Now×
Log in
If you created your account with Google or Facebook
Don't have an account?
Forgot your password?
No Problem

Simply enter the email address you used to create your account and click "Reset Password". You will receive additional instructions via email.

Forgot your username? If so please contact customer support at (510) 658-9252

Password Reset Confirmation

Password Reset Instructions have been sent to

Subscribe to The Weekender
Get the week's leading headlines delivered straight to your inbox.
Top headlines from around the real estate industry. Breaking news as it happens.
15 stories covering tech, special reports, video and opinion.
Unique features from hacker profiles to portal watch and video interviews.
Unique features from hacker profiles to portal watch and video interviews.
It looks like you’re already a Select Member!
To subscribe to exclusive newsletters, visit your email preferences in the account settings.
Up-to-the-minute news and interviews in your inbox, ticket discounts for Inman events and more
1-Step CheckoutPay with a credit card
By continuing, you agree to Inman’s Terms of Use and Privacy Policy.

You will be charged . Your subscription will automatically renew for on . For more details on our payment terms and how to cancel, click here.

Interested in a group subscription?
Finish setting up your subscription