Showing posts with label crises. Show all posts
Showing posts with label crises. Show all posts

Monday, April 29, 2013

How to misunderstand crises... with Rational Expectations

** UPDATE BELOW ** I've just about finished Gary Gorton's excellent book Misunderstanding Financial Crises. I think it's the most convincing book I've read so far that links the mechanisms of the recent crisis to crises in the past. In effect, he argues that the crisis was the direct result of the uncontrolled creation of money by the shadow banking sector, and ultimately took place as a classic bank run, no different from runs in the past, except that this run took place mostly out of public view because it didn't involve ordinary bank deposits. The new kind of money in this bank run was stuff such as repo agreements and commercial paper which played the role of money for financial institutions. In 2007-2008, when lenders lost confidence (for good reason) in the mortgage-backed collateral backing this money, they demanded that money back, and the financial system seized up.

The explanation is convincing and wholly natural. The argument is most convincing because Gorton does a masterful job of placing this bank run in the context of the long history of past runs. And also because Gorton, as an economist, places blame squarely on the economics profession (himself included) for being asleep at the wheel:
Think of economists and bank regulators looking out at the financial landscape prior to the financial crisis. What did they see? They did not see the possibility of a systemic crisis. Nor did they see how capital markets and the banking system had evolved in the last thirty years. They did not know of the existence of new financial instruments or the size of certain money markets. They did not know what "money" had become. They looked from a certain point of view, from a certain paradigm, and missed everything that was important... The blindness is astounding. That economists did not think such a crisis could happen in the United States was an intellectual failure.

It seems to me that there is a certain amount of denial among economists. I have noticed, in talking about the ideas in this book with my economist colleagues, that there is a fairly clear generational divide on this. To younger economists and graduate students, it is obvious that there was an intellectual failure. Some older economists are inclined to hem and haw, resorting to farfetched rebuttals. It is clear that this is a sensitive issue, as like banks no one wants to have to write down the value of their capital.
The book gets rather technical in places talking about the details of day to day financing on Wall St., but all in a way that adds credibility to the main argument.

One other thing of interest. Gorton in a late chapter, when discussing the spectacular failure of the rational expectations paradigm, quotes University of Chicago economist James Heckman, winner of the economics' Nobel Prize (yes, that's not its actual name) in 2000, from an interview he did with John Cassidy in 2010. I hadn't come across the interview before. It's a fascinating read and gives some interesting perspective on varied views held by economists within the Chicago department (Cassidy's words in italics):
What about the rational-expectations hypothesis, the other big theory associated with modern Chicago? How does that stack up now?

I could tell you a story about my friend and colleague Milton Friedman. In the nineteen-seventies, we were sitting in the Ph.D. oral examination of a Chicago economist who has gone on to make his mark in the world. His thesis was on rational expectations. After he’d left, Friedman turned to me and said, “Look, I think it is a good idea, but these guys have taken it way too far.”

It became a kind of tautology that had enormously powerful policy implications, in theory. But the fact is, it didn’t have any empirical content. When Tom Sargent, Lard Hansen, and others tried to test it using cross equation restrictions, and so on, the data rejected the theories. There were a certain section of people that really got carried away. It became quite stifling.

What about Robert Lucas? He came up with a lot of these theories. Does he bear responsibility?

Well, Lucas is a very subtle person, and he is mainly concerned with theory. He doesn’t make a lot of empirical statements. I don’t think Bob got carried away, but some of his disciples did. It often happens. The further down the food chain you go, the more the zealots take over.

What about you? When rational expectations was sweeping economics, what was your reaction to it? I know you are primarily a micro guy, but what did you think?

What struck me was that we knew Keynesian theory was still alive in the banks and on Wall Street. Economists in those areas relied on Keynesian models to make short-run forecasts. It seemed strange to me that they would continue to do this if it had been theoretically proven that these models didn’t work.

What about the efficient-markets hypothesis? Did Chicago economists go too far in promoting that theory, too?

Some did. But there is a lot of diversity here. You can go office to office and get a different view.

[Heckman brought up the memoir of the late Fischer Black, one of the founders of the Black-Scholes option-pricing model, in which he says that financial markets tend to wander around, and don’t stick closely to economics fundamentals.]

[Black] was very close to the markets, and he had a feel for them, and he was very skeptical. And he was a Chicago economist. But there was an element of dogma in support of the efficient-market hypothesis. People like Raghu [Rajan] and Ned Gramlich [a former governor of the Federal Reserve, who died in 2007] were warning something was wrong, and they were ignored. There was sort of a culture of efficient markets—on Wall Street, in Washington, and in parts of academia, including Chicago.

What was the reaction here when the crisis struck?

Everybody was blindsided by the magnitude of what happened. But it wasn’t just here. The whole profession was blindsided. I don’t think Joe Stiglitz was forecasting a collapse in the mortgage market and large-scale banking collapses.

So, today, what survives of the Chicago School? What is left?

I think the tradition of incorporating theory into your economic thinking and confronting it with data—that is still very much alive. It might be in the study of wage inequality, or labor supply responses to taxes, or whatever. And the idea that people respond rationally to incentives is also still central. Nothing has invalidated that—on the contrary.

So, I think the underlying ideas of the Chicago School are still very powerful. The basis of the rocket is still intact. It is what I see as the booster stage—the rational-expectation hypothesis and the vulgar versions of the efficient-markets hypothesis that have run into trouble. They have taken a beating—no doubt about that. I think that what happened is that people got too far away from the data, and confronting ideas with data. That part of the Chicago tradition was neglected, and it was a strong part of the tradition.

When Bob Lucas was writing that the Great Depression was people taking extended vacations—refusing to take available jobs at low wages—there was another Chicago economist, Albert Rees, who was writing in the Chicago Journal saying, No, wait a minute. There is a lot of evidence that this is not true.

Milton Friedman—he was a macro theorist, but he was less driven by theory and by the desire to construct a single overarching theory than by attempting to answer empirical questions. Again, if you read his empirical books they are full of empirical data. That side of his legacy was neglected, I think.

When Friedman died, a couple of years ago, we had a symposium for the alumni devoted to the Friedman legacy. I was talking about the permanent income hypothesis; Lucas was talking about rational expectations. We have some bright alums. One woman got up and said, “Look at the evidence on 401k plans and how people misuse them, or don’t use them. Are you really saying that people look ahead and plan ahead rationally?” And Lucas said, “Yes, that’s what the theory of rational expectations says, and that’s part of Friedman’s legacy.” I said, “No, it isn’t. He was much more empirically minded than that.” People took one part of his legacy and forgot the rest. They moved too far away from the data.

** UPDATE **

On a closely related note, check out between 18:00 and about 20:25 of this video documentary on debt and its primary role in the crisis, link courtesy of Lars Syll. Robert Lucas asserts (around 19:40) that debt just doesn't matter because the level of debt and credit always "cancels out." He seems to think it is strange that anyone could even think that debt should matter, as if he's completely blind to the massive agony and social upheaval ensuing from foreclosures and failed businesses around the US and the world. Lars suggests this is "unbelievable stupidity" and it is certainly unbelievable, but I think maybe it is less stupidity and reflects more a kind of borderline autistic inability to make a distinction between some extremely abstract mathematical model and actual economic reality. In Lucas's models, I suspect that debt and credit do always cancel out. Which is one aspect of what makes those models quite useless for many purposes, and dangerous in the hands of anyone who takes them too seriously.  

Thursday, July 21, 2011

Of Idols and Crises

Here's a quote of the day, perhaps the best metaphor I've heard for where we are now in this financial and economic crisis, a few years downstream of the initial fractures, as authorities (and bankers) in Europe are still trying to duck necessary pain and loss through clever financial slight of hand. From novelist John Lanchester, quoted in Business & Finance:
"It's like there was a giant rumbling noise, the foundations shook, there was a crack in the altar and the golden idol fell down," he says. "And then there was a silence as they picked up the idol, polished it and put it back on the altar and now they're hoping that nobody had noticed. The fact is, we've had three or four supposedly unprecedented crises in the last couple of decades, and these events seem to be getting bigger and more frequent. That suggests to me that we really need to fix the whole architecture of world capitalism, but nothing I've heard suggests that anybody's doing that." 
Truly, nobody is doing that. For the moment, in Greece, in the US, and elsewhere, everything is patchwork, a few small repairs, even the illusion of repairs, and that's it.

Friday, July 15, 2011

Leverage control for market stability

I listened today to a number of extremely informative talks at a workshop in Durham (UK) on Tipping Points in Financial Systems (description here part way down the page). I'll make some comments on the various talks in coming days. But it might be worth noting a few observations on some further progress on a model of market volatility -- and its inherent link to leverage -- achieved by Stefan Thurner and colleagues.

I wrote about this work several years ago in an OpEd for the New York Times, and also in this thing for Nature, but today learned about some further developments which seem particularly important. The model developed in this work makes the point that saavy participants in speculative markets (call them "hedge funds," but they could banks or just one individual) can use leverage to deliver higher returns and thereby attract more investors. This is obvious and natural. Many details aside, however, the model showed that the competition between funds to attract investors drives a race to higher leverage, increasing market volatility, and the eventual probability of violent market crashes. Leverage is dangerous and comes with systemic costs.

This can be seen (in an abstract way, sorry) from the figure below from the paper. In a long simulation of the market, this shows that the likelihood of finding market returns (absolute value of the logarithm of prices differences over a short time) exceeding a value R. The red is how the market works when leverage is low -- the probability to see really big market movements, R > 0.1 or so, is extremely small. But as hedge funds evolve to use significant leverage, the market moves into a regime described instead by the blue curve -- the probability of tail events and extreme movements becomes orders of magnitude larger.


The implication is clear: leverage causes volatility.

But Thurner suggested today that intermediate levels of leverage actually reduce market volatility, because it makes it easier for the saavy hedge fund investors to pounce on and wipe out market mispricings. This is an interesting point and one worth pondering. I haven't yet digested the latter parts of the updated paper, which now considers several policy moves and how they influence volatility, but the results have the wonderful ambiguity that one learns to expect in confronting complex systems. For example, capping leverage at intermediate levels (factors of around 10) is in some case worse than capping it at higher levels (around 15). Controls on the capital reserves held by the funds (or banks) also have some ambiguous results -- in some cases, making them hold higher reserves can lead to more volatility in the market, not less. Weird.

I'll try to digest this new work and report on it's implications once I understand them more clearly, but they already demonstrate the point that our intuition isn't so good at seeing the link between interventions in markets and the likely consequences. I'm certainly guilty on occasion of thinking that if the financial industry is against any proposed regulation, then it must be a good one. Often that's not a bad rule of thumb. But if we're really going to make progress in making markets work for everyone, we need to think very carefully -- and back up proposals with hard evidence. This work is developing such evidence.

Thursday, July 7, 2011

Bank runs begin in Greece and Ireland

Gavyn Davies refers to the image below, which presents a rather disturbing trend in bank deposits in Greece and Ireland. Notably, banks in these two countries in the past year or two have experienced a sharp increase in withdrawals of retail deposits:



Davies suggests they've lost 15% of their deposits, but it could be significantly worse than that -- note that the data in the figure only goes up to around December 2010. Extrapolate the trend through to today and I'm guessing the loss is approaching 30-35%.

Fully one third of the retails deposits in these two nations have been pulled out?! Yikes. Not a good sign. As Davies comments:
As the UK government found in the case of Northern Rock, the appearance of queues outside banks is one of the worst nightmares which a central bank can face. It has not happened in Europe – yet.