Forget about particular details for a moment, in conceptual terms what led so many financial institutions to take so much excess risk?  Bob Frank addresses that question and here is my list of major factors:

1. Collective stupidity: A lot of Greeks believed in Zeus and a lot of people in 1938 thought Hitler would be good for Germany.  They were just plain, flat out wrong.  I’ll also put "model error" under this heading.  The relevant stupidity concerned both the fate of home prices and the degree of acceptable leverage.

2. Writing the naked put: This is Bob Frank’s main explanation, noting that he uses different terminology and adds a relative status dash to the argument.  If you don’t know options theory, just imagine betting against the Washington Wizards to win the NBA title every year.  For a lot of years you’ll earn super-normal returns, but one year (not anytime soon, I can assure you) you’ll be wiped out.  That is essentially the strategy the banks were playing.  They were going "short on volatility," so to speak.  In the meantime they reaped high returns and some amazing perks for private life.  It’s hard to just call the party to an end, even if you have a relatively long time horizon.

3. The neutering of debtors. This is the sophisticated form of the moral hazard argument.  Bailouts mean that debtors and depositors don’t have enough incentive to keep safe the firms they give their money to.  Note that #3, as a corollary, suggests that equity holders do not on their provide adequate safeguards against a crash.

Evaluation: You can pin most of the blame on #3 provided you think that a) our government really could let these firms default on their debts ex post and b) society is willing to live with significantly less liquidity transformation up front and also lower returns for depositors.  I reject this mix for reasons of time inconsistency, namely that ex post the bailout is always on its way so this is simply something we have to live with. 

You’re left with #1 and #2 but it is hard to assign relative weights because they work together.  The people earning money under #2 won’t work terribly hard to disillusion the fools and frauds operating under #1.

At times I am tempted to add #4 to the mix:

4. The increasing value of human capital: Bankruptcy is no longer so painful for the wealthy.  You can always get another high-paying job plus you have $10 million squirreled away somewhere in Switzerland.  You could end up working for the guv’ment for $130K a year and your life still is pretty good once you get over the shock of adjustment.  So why not take lots of risk and try to get ahead of the other guy?

The full story then involves additional resources being put on the table — for possible risky investment — as a result of easy monetary policy, pro-housing government policies, the global savings glut, and simple bad luck.  I’ll cover those factors in more detail soon.  And I’ll also have more to say about some of the details of mortgage-backed securities and accounting practices and regulation; those were factors too, although not at the level of generality I am covering here.

Addendum: Here’s Mark Thoma and Barry Ritzholz.  In the comments Robert Feinman is square on, read him.

Second addendum: Megan McArdle adds quite a bit.

It turns out there won’t be one.  In fact we are seeing the opposite:

"We will work cooperatively and in a coordinated way within the
European Union and with our international partners," it [the statement] added. "In the
spirit of close cooperation within the European Union, we will ensure
that potential cross-border effects of national decisions are taken
into consideration."

This language was seen as a rebuke to Ireland, which last week
decided to offer guarantees to all Irish depositors. The decision,
taken unilaterally, irked Brown and his lieutenants in London, who
feared it might lead Britons to pull their money out of British banks
and put it in Irish banks instead to enjoy the guarantee.

British depositors were already crowding to get into the nationalized Northern Rock but they were turned away at the proverbial door.  Other news is that the German government-led bank consortium to rescue Hypo Bank has fallen apart, not a good sign.  The German government has today moved to guarantee all "private savings deposits" [private Sparanlagen], also not a good sign.  Which other countries will now follow suit?  All of them?  Europe as a whole lacks a safe asset as focal, liquid, and available as T-Bills and now that is becoming a problem.

Gartner’s keys to success as a supplier in reverse auctions are: (a)
Thorough preparation – it’s essential to know your costs, your
suppliers, and your market to the greatest extent possible – tiny
details can make the difference between winning and losing, and between
being profitable or not; (b) Reverse auctions should be largely kept to
the supply of commodity products rather than proprietary ones; and (c)
Having a strong, competent bidder leading your effort at the time of
the auction, with clear guidelines on when to bid and when to fold is
essential.

Anticipating Hank Paulson, Gartner adds:

"I know most people don’t look at reverse auctions positively, but we see them as a process that makes you better,"

Here is the link.  The article will soon be much longer.  Here is a website devoted to summarizing the research against reverse auctions; it appears unrelated to critiques of Paulson and the Paulson plan.  It seems to be fighting a personal war and so I doubt its objectivity:

The bottom line is BUYERS should not use reverse auctions because the amount of savings that can actually be achieved is greatly overstated. In addition, reverse auctions create numerous other problems for buyers.  SELLERS should not participate in reverse auctions because there is nothing in it for them; especially incumbent suppliers. In almost every case, neither buyers nor sellers benefit from this purchasing tool because it is an unhealthy continuation of zero sum power-based bargaining that degrades the competitiveness of both parties. Reverse auctions are undeniably a bad purchasing practice and a wrong approach to spend management.

I hope to soon consider other research on reverse auctions.

Greg Mankiw shows that real interest rates are rising on inflation-adjusted government bonds.  Paul Krugman shows that short-term Treasury yields are down.  The state of California cannot get short-term financing.  There is simply no one willing to lend.  Yet I would have no trouble buying a second home and getting another mortgage at a reasonable rate of interest and I am hardly a rich man.

Credit market segmentation is always there but it doesn’t usually matter this much.  The parts of the credit market that are paralyzed by fear are the major problem right now.  And until that problem is cleared up, we will witness a step-by-step disembowelment of the American economy. 

The clock is ticking.  We need very rapidly to get to the point where natural lenders are willing to lend and "cross-market arbitrage" is no longer a dirty word.

A new blog to track the financial crisis.  It provides a good overview of mainstream sources and general background.  By the way, they point to this IMF paper on previous international crises.

Hat tip to Fimoculous blog.

Here is Franklin Allen and Elena Carletti, circa 2006:

When liquidity plays an important role as in times of financial crisis, asset prices in some markets may reflect the amount of liquidity available in the market rather than the future earning power of the asset. Mark-to-market accounting is not a desirable way to assess the solvency of a financial institution in such circumstances. We show that a shock in the insurance sector can cause the current value of banks’ assets to be less than the current value of their liabilities so the banks are insolvent. In contrast, if historic cost accounting is used, banks are allowed to continue and can meet all their future liabilities. Mark-to-market accounting can thus lead to contagion where none would occur with historic cost accounting.

Here is a comment on that same paper.  I thank Scott Cunningham for the pointer.

The consensus among economists is now clear, the best strategy for dealing with the financial crisis is to recapitalize the banks that need recapitalization.  Paul Krugman, John Cochrane, Luigi Zingales, Douglas Diamond, Raghuram Rajan and many others all advocate some form of recapitalization as do Tyler Cowen and myself.  Krugman would prefer a recapitalization in the form of nationalization.  In my view, there is still plenty of private money to buy banks at the right price and my preferred model is the FDIC leading a speed bankruptcy procedure, as was done brilliantly with Washington Mutual (Cochrane also supports this model.)  In the middle are most of the others who have a variety of good ideas to require the banks to raise equity in various ways. 

The consensus policy of economists would put most of the burden of adjustment on politically powerful holders of equity and bonds.

There is also a consensus among economists that the bailout bill is not the right policy.  None of the above economists, for example, is enthusiastic about the bailout.  My bet is that all of us think that the bailout has a substantial likelihood of failing.  The support that exists is born out of hope and fear not judgment and experience.  Nevertheless, the political consensus is that a bailout is what we will get whether it is likely to work or not.   

Addendum: Lynne Kiesling draws the Olsonian conclusion.

It is now on-line.  Contributors include Armen Alchian, Gary Becker, Avinash Dixit, Claudia Goldin, Greg Mankiw, Paul Romer, Pete Boettke, Tyler Cowen, Bryan Caplan, Russ Roberts and many others.

On another topic, from elsewhere, here is Arnold Kling on net worth certificates.  And here is Russ Roberts on home prices.  Here is Bill Easterly’s Op-Ed on development and the crash.

A second view is that because the methodologies used for rating CDOs are complex, arbitrary, and opaque, they create opportunities for parties to create a ratings “arbitrage” opportunity without adding any actual value. It is difficult to test this view, too, although there are reasons to find it persuasive. Essentially, the argument is that once the rating agencies fix a given set of formulas and variables for rating CDOs, financial market participants will be able to find a set of fixed income assets that, when run through the relevant models, generate a CDO whose tranches are more valuable than the underlying assets. Such a result might be due to errors in rating the assets themselves (that is, the assets are cheap relative to their ratings), errors in calculating the relationship between those assets and the tranche payouts (that is, the correlation and expected payout of the assets appear to be higher and therefore support higher ratings of tranches), or errors in rating the individual CDO tranches (that is, the tranches receive a higher rating than they deserve, given the ratings of the underlying assets). These arguments are complex and subtle…

That is from a very interesting paper by Frank Partnoy.  The paper is not always easy reading but so far it is the best piece on its topic I have found.  This was another good section:

If the mathematical models have serious limitations, how could they support a $5 trillion market? Some experts have suggested that CDO structurers manipulate models and the underlying portfolio in order to generate the most attractive ratings profile for a CDO. For example, parties included the bonds of General Motors and Ford in CDOs before they were downgraded because they were cheap relative to their (then high) ratings.67 The primary reason that the downgrades of those companies had an unexpectedly large market impact was that they were held by so many CDOs.

Thus, with respect to structured finance, credit rating agencies have been functioning more like “gate openers” rather than gatekeepers. The agencies are engaged in a business, the rating of CDOs, which is radically different from the core business of other gatekeepers. No other gatekeeper has created a dysfunctional multi-trillion dollar market, built on its own errors and limitations.

There is also a good discussion of how the ratings agencies have claimed First Amendment protection for their activities, more or less successfully.  p.96 offers some good policy conclusions.