Sharing risk can increase risk

I have a column coming out in Bloomberg Views sometime this evening (US time). It touches on the European debt crisis and the issue of outstanding credit default swaps. This post is intended to provide a few more technical details on the study by Stefano Battiston and colleagues, which I mention in the column, showing that more risk sharing between institutions can, in some cases, lead to greater systemic risk. [Note: this work was carried out as part of an ambitious European research project called Forecasting Financial Crises, which brings together economists, physicists, computer scientists and others in an effort to forge new insights into economic systems by exploiting ideas from other areas of science.]

The authors of this study start out by noting the obvious: that credit networks can both help institutions to pool resources to achieve things they couldn't on their own, and to diversify against the risks they face. At the same time, the linking together of institutions by contracts implies a greater chance for the propagation of financial stress from one place to another. The same thing applies to any network such as the electrical grid -- sharing demands among many generating stations makes for a more adaptive and efficient system, able to handle fluctuations in demand, yet also means that failures can spread across much of the network very quickly. New Orleans can be blacked out in a few seconds because a tree fell in Cleveland.

In banking, the authors note, Allen and Gale (references given in the paper) did some pioneering work on the properties of credit networks:

... in their pioneering contribution Allen and Gale reach the conclusion that if the credit network of the interbank market is a credit chain – in which each agent is linked only to one neighbor along a ring – the probability of a collapse of each and every agent (a bankruptcy avalanche) in case a node is hit by a shock is equal to one. As the number of partners of each agent increases, i.e. as the network evolves toward completeness, the risk of a collapse of the agent hit by the shock goes asymptotically to zero, thanks to risk sharing. The larger the pool of connected neighbors whom the agent can share the shock with, the smaller the risk of a collapse of the agent and therefore of the network, i.e. the higher network resilience. Systemic risk is at a minimum when the credit network is complete, i.e. when agents fully diversify individual risks. In other words, there is a monotonically decreasing relationship between the probability of individual failure/systemic risk and the degree of connectivity of the credit network.

This is essentially the positive story of risk sharing which is taken as the norm in much thinking about risk management. More sharing is better; the probability of individual failure always decreases as the density of risk-sharing links grows.

This is not what Battiston and colleagues find under slightly more general assumptions of how the network is put together and how institutions interact. I'll give a brief outline of what is different in their model in a moment; what comes out of it is the very different conclusion that...

The larger the number of connected neighbors, the smaller the risk of an individual collapse but the higher systemic risk may be and therefore the lower network resilience. In other words, in our paper, the relationship between connectivity and systemic risk is not monotonically decreasing as in Allen and Gale, but hump shaped, i.e. decreasing for relatively low degree of connectivity and increasing afterwards.

 Note that they are making a distinction between two kinds of risk: 1. individual risk, arising from factors specific to one bank's business and which can make it go bankrupt, and 2. systemic risk, arising from the propagation of financial distress through the system. As in Allen and Gale, they find that individual risk DOES decrease with increasing connectivity: banks become more resistant to shocks coming from their own business, but that systemic risk DOES NOT decrease. The latter risk increases with higher connectivity, and can win out in determining the overall chance a bank might go bankrupt. In effect, the effort on the part of many banks to manage their own risks can end up creating a new systemic risk that is worse than the risk they have reduced through risk sharing.

There are two principle elements in the credit network model they study. First is the obvious fact that resilience of an institution in such a network depends on the resilience of those with whom it shares risks. Buying CDS against the potential default of your Greek bonds is all well and good as long as the bank from whom you purchased the CDS remains solvent. In the 2008 crisis, Goldman Sachs and other banks had purchased CDS from A.I.G. to cover their exposure to securitized mortgages, but those CDS would have been more or less without value had the US government not stepped in to bail out A.I.G.

The second factor model is very important, and it's something I didn't have space to mention in the Bloomberg essay. This is the notion that financial distress tends to have an inherently nonlinear aspect to it -- some trouble or distress tends to bring more in its wake. Battiston and colleagues call this "trend reinforcement, " and describe it as follows:

... trend reinforcement is also quite a general mechanism in credit networks. It can occur in at least two situations. In the first one (see e.g. in (Morris and Shin, 2008)), consider an agent A that is hit by a shock due a loss in value of some securities among her assets. If such shock is large enough, so that some of A’s creditors claim their funds back, A is forced to fire-sell some of the securities in order to pay the debt. If the securities are sold below the market price, the asset side of the balance sheet is decreasing more than the liability side and the leverage of A is unintentionally increased. This situation can lead to a spiral of losses and decreasing robustness (Brunnermeier, 2008; Brunnermeier and Pederson, 2009). A second situation is the one in which when the agent A is hit by a shock, her creditor B makes condition to credit harder in the next period. Indeed it is well documented that lenders ask a higher external finance premium when the borrowers’ financial conditions worsen (Bernanke et al., 1999). This can be seen as a cost from the point of view of A and thus as an additional shock hitting A in the next period. In both situations, a decrease in robustness at period t increases the chance of a decrease in robustness at period t + 1.

It is the interplay of such positive feedback with the propagation of distress in a dense network which causes the overall increase in systemic risk at high connectivity.

I'm not going to wade into the detailed mathematics. Roughly speaking, the authors develop some stochastic equations to follow the evolution of a bank's "robustness" R -- considered to be a number between 0 and 1, with 1 being fully robust. A bankruptcy event is marked by R passing through 0. This is a standard approach in the finance literature on modeling corporate bankruptcies. The equations they derive incorporate their assumptions about the positive influences of risk sharing and the negative influences of distress propagation and trend reinforcement.

The key result shows up clearly in the figure (below), which shows the overall probability of a bank in the network to go bankrupt (a probability per unit of time) versus the amount of risk-sharing connectivity in the network (here given by k, the number of partners with which each bank shares risks). It may not be easy to see, but the figure shows a dashed line (labeled 'baseline') which reflects the classical result on risk sharing in the absence of trend reinforcement. More connectivity is always good. But the red curve shows the more realistic result with trend reinforcement or the positive feedback associated with financial distress taken into account. Now adding connectivity is only good for a while, and eventually becomes positively harmful. There's a middle range of optimal connectivity beyond which more connections only serve to put bank in greater danger.
 

Finally, the authors of this paper make very interesting observations about the potential relevance of this model to globalization, which has been an experiment in risk sharing on a global scale, with an outcome -- at the moment -- which appears not entirely positive:

In a broader perspective, this conceptual framework may have far reaching implications also for the assessment of the costs and benefits of globalization. Since some credit relations involve agents located in different countries, national credit networks are connected in a world wide web of credit relationships. The increasing interlinkage of credit networks – one of the main features of globalization – allows for international risk sharing but it also makes room for the propagation of financial distress across borders. The recent, and still ongoing, financial crisis is a case in point.

International risk sharing may prevail in the early stage of globalization, i.e. when connectivity is relatively ”low”. An increase in connectivity at this stage therefore may be beneficial. On the other hand, if connectivity is already high, i.e. in the mature stage of globalization, an increase in connectivity may bring to the fore the internationalization of financial distress. An increase in connectivity, in other words, may increase the likelihood of financial crises worldwide.

Which is, in part, why we're not yet out of the European debt crisis woods.

Central corporate control revealed by mathematics

If you haven't already heard about this new study on the network of corporate control, do have a look. The idea behind it was to use network analysis of who owns whom in the corporate world (established through stock ownership) to tease out centrality of control. New Scientist magazine offers a nice account, which starts as follows:

AS PROTESTS against financial power sweep the world this week, science may have confirmed the protesters' worst fears. An analysis of the relationships between 43,000 transnational corporations has identified a relatively small group of companies, mainly banks, with disproportionate power over the global economy.

The study's assumptions have attracted some criticism, but complex systems analysts contacted by New Scientist say it is a unique effort to untangle control in the global economy. Pushing the analysis further, they say, could help to identify ways of making global capitalism more stable.

The idea that a few bankers control a large chunk of the global economy might not seem like news to New York's Occupy Wall Street movement and protesters elsewhere (see photo). But the study, by a trio of complex systems theorists at the Swiss Federal Institute of Technology in Zurich, is the first to go beyond ideology to empirically identify such a network of power. It combines the mathematics long used to model natural systems with comprehensive corporate data to map ownership among the world's transnational corporations (TNCs).

But also have a look at the web site of the project behind the study, the European project Forecasting Financial Crises, where the authors have tried to clear up several common misinterpretations of just what the study shows.

Indeed, I know the members of this group quite well. They're great scientists and this is a beautiful piece of work. If you know a little about natural complex networks, then the structures found here actually aren't terrifically surprising. However, they are interesting, and it's very important to have the structure documented in detail. Moreover, just because the structure observed here is very common in real world complex networks doesn't mean its something that is good for society.

Hating bankers and the "Unholy Alliance" -- the long history

An excellent if brief article at Salon.com gives some useful historical context to the current animosity toward bankers -- it's nothing new. Several interesting quotes from key figures in the past:

“Behind the ostensible government sits enthroned an invisible government owing no allegiance and acknowledging no responsibility to the people. To destroy this invisible government, to befoul this unholy alliance between corrupt business and corrupt politics is the first task of statesmanship.”

Theodore Roosevelt, 1912

“We have in this country one of the most corrupt institutions the world has ever known. I refer to the Federal Reserve Board and the Federal Reserve Banks. The Federal Reserve Board, a Government board, has cheated the Government of the United States and the people of the United States out of enough money to pay the national debt. The depredations and the iniquities of the Federal Reserve Board and the Federal Reserve banks acting together have cost this country enough money to pay the national debt several times over…

“Some people think the Federal Reserve Banks are United States Government institutions. They are not Government institutions. They are private credit monopolies, which prey upon the people of the United States for the benefit of themselves and their foreign customers, foreign and domestic speculator sand swindlers, and rich and predatory money lenders.”

Louis McFadden, chairman of the House Committee on Banking and Currency, 1932

I should have known this, but didn't -- the Federal Reserve Banks are not United States Government institutions. They are indeed owned by the private banks themselves, even though the Fed has control over taxpayer funds.This seems dubious in the extreme to me, although I'm sure there are many arguments to consider. Memory recalls reading arguments about the required independence of the central bank, but independence is of course not the same as "control by the private banks." Maybe we need to change the governance of the Fed and install some oversight with real power from a non-banking non-governmental element.

And my favourite:

“Banks are an almost irresistible attraction for that element of our society which seeks unearned money.”

FBI head J. Edgar Hoover, 1955.

In recent years, the attraction has been very strong indeed.

This is why knowing history is so important. Many battles have been fought before.

Matt Taibbi on OWS

Don't miss this post by Matt Taibbi on the Occupy Wall St. movement and its roots as an anti-corruption movement:

People aren't jealous and they don’t want privileges. They just want a level playing field, and they want Wall Street to give up its cheat codes, things like:

FREE MONEY. Ordinary people have to borrow their money at market rates. Lloyd Blankfein and Jamie Dimon get billions of dollars for free, from the Federal Reserve. They borrow at zero and lend the same money back to the government at two or three percent, a valuable public service otherwise known as "standing in the middle and taking a gigantic cut when the government decides to lend money to itself."

Or the banks borrow billions at zero and lend mortgages to us at four percent, or credit cards at twenty or twenty-five percent. This is essentially an official government license to be rich, handed out at the expense of prudent ordinary citizens, who now no longer receive much interest on their CDs or other saved income. It is virtually impossible to not make money in banking when you have unlimited access to free money, especially when the government keeps buying its own cash back from you at market rates.

Your average chimpanzee couldn't fuck up that business plan, which makes it all the more incredible that most of the too-big-to-fail banks are nonetheless still functionally insolvent, and dependent upon bailouts and phony accounting to stay above water. Where do the protesters go to sign up for their interest-free billion-dollar loans?

CREDIT AMNESTY. If you or I miss a $7 payment on a Gap card or, heaven forbid, a mortgage payment, you can forget about the great computer in the sky ever overlooking your mistake. But serial financial fuckups like Citigroup and Bank of America overextended themselves by the hundreds of billions and pumped trillions of dollars of deadly leverage into the system -- and got rewarded with things like the Temporary Liquidity Guarantee Program, an FDIC plan that allowed irresponsible banks to borrow against the government's credit rating.

This is equivalent to a trust fund teenager who trashes six consecutive off-campus apartments and gets rewarded by having Daddy co-sign his next lease. The banks needed programs like TLGP because without them, the market rightly would have started charging more to lend to these idiots. Apparently, though, we can’t trust the free market when it comes to Bank of America, Goldman, Sachs, Citigroup, etc.

In a larger sense, the TBTF banks all have the implicit guarantee of the federal government, so investors know it's relatively safe to lend to them -- which means it's now cheaper for them to borrow money than it is for, say, a responsible regional bank that didn't jack its debt-to-equity levels above 35-1 before the crash and didn't dabble in toxic mortgages. In other words, the TBTF banks got better credit for being less responsible. Click on freecreditscore.com to see if you got the same deal.

STUPIDITY INSURANCE. Defenders of the banks like to talk a lot about how we shouldn't feel sorry for people who've been foreclosed upon, because it's they're own fault for borrowing more than they can pay back, buying more house than they can afford, etc. And critics of OWS have assailed protesters for complaining about things like foreclosure by claiming these folks want “something for nothing.”

This is ironic because, as one of the Rolling Stone editors put it last week, “something for nothing is Wall Street’s official policy." In fact, getting bailed out for bad investment decisions has been de rigeur on Wall Street not just since 2008, but for decades.

Time after time, when big banks screw up and make irresponsible bets that blow up in their faces, they've scored bailouts. It doesn't matter whether it was the Mexican currency bailout of 1994 (when the state bailed out speculators who gambled on the peso) or the IMF/World Bank bailout of Russia in 1998 (a bailout of speculators in the "emerging markets") or the Long-Term Capital Management Bailout of the same year (in which the rescue of investors in a harebrained hedge-fund trading scheme was deemed a matter of international urgency by the Federal Reserve), Wall Street has long grown accustomed to getting bailed out for its mistakes.

The 2008 crash, of course, birthed a whole generation of new bailout schemes. Banks placed billions in bets with AIG and should have lost their shirts when the firm went under -- AIG went under, after all, in large part because of all the huge mortgage bets the banks laid with the firm -- but instead got the state to pony up $180 billion or so to rescue the banks from their own bad decisions.

This sort of thing seems to happen every time the banks do something dumb with their money...

 More at the link.

Abolish banks? Maybe, maybe not...

I have little time to post this week as I have to meet several writing deadlines, but I wanted to briefly mention  this wonderful and extremely insightful speech by Adair Turner from last year (there's a link to the video of the speech here). Turner offers so many valuable perspectives that the speech is worth reading and re-reading; here are a few short highlights that caught my attention.

First, Turner mentions that the conventional wisdom about the wonderful self-regulating efficiency of markets is really a caricature of the real economic theory of markets, which notes many possible shortcomings (asymmetric information, incomplete markets, etc.). However, he also notes that this conventional wisdom is still what has been most influential in policy circles:

.. why, we might ask, do we need new economic thinking when old economic thinking has been so varied and fertile? ... Well, we need it because the fact remains that while academic economics included many strains, in the translation of ideas into ideology, and ideology into policy and business practice, it was one oversimplified strain which dominated in the pre-crisis years.

What was that "oversimplified strain"? Turner summarizes it as follows:

For over half a century the dominant strain of academic economics has been concerned with exploring, through complex mathematics, how economically rational human beings interact in markets. And the conclusions reached have appeared optimistic, indeed at times panglossian. Kenneth Arrow and Gerard Debreu illustrated that a competitive market economy with a fully complete set of markets was Pareto efficient. New classical macroeconomists such as Robert Lucas illustrated that if human beings are not only rational in their preferences and choices but also in their expectations, then the macro economy will have a strong tendency towards equilibrium, with sustained involuntary unemployment a non-problem. And tests of the efficient market hypothesis appeared to illustrate that liquid financial markets are not driven by the patterns of chartist fantasy, but by the efficient processing of all available information, making the actual price of a security a good estimate of its intrinsic value.

As a result, a set of policy prescriptions appeared to follow:

· Macroeconomic policy – fiscal and monetary – was best left to simple, constant and clearly communicated rules, with no role for discretionary stabilisation.

· Deregulation was in general beneficial because it completed more markets and created better incentives.

· Financial innovation was beneficial because it completed more markets, and speculative trading was beneficial because it ensured efficient price discovery, offsetting any temporary divergences from rational equilibrium values.

· And complex and active financial markets, and increased financial intensity, not only improved efficiency but also system stability, since rationally self-interested agents would disperse risk into the hands of those best placed to absorb and manage it.

In other words, all the nuances of the economic theories showing the many limitations of markets seem to have made little progress in getting into the minds of policy makers, thwarted by ideology and the very simple story espoused by the conventional wisdom. Insidiously, the vision of efficient markets so transfixed people that it was assumed that the correct policy prescriptions must be those which would take the system closer to the theoretical ideal (even if that ideal was quite possibly a theorist's fantasy having little to do with real markets), rather than further away from it:

What the dominant conventional wisdom of policymakers therefore reflected was not a belief that the market economy was actually at an Arrow-Debreu nirvana – but the belief that the only legitimate interventions were those which sought to identify and correct the very specific market imperfections preventing the attainment of that nirvana. Transparency to reduce the costs of information gathering was essential: but recognising that information imperfections might be so deep as to be unfixable, and that some forms of trading activity might be socially useless, however transparent, was beyond the ideology...

Turner goes on to argue that the more nuanced views of markets as very fallible systems didn't have much influence mostly because of ideology and, in short, power interests on the part of Wall St., corporations and others benefiting from deregulation and similar policies. I think it is also fair to say that economists as a whole haven't done a very good job of shouting loudly that markets cannot be trusted to know best or that they will only give good outcomes in a restricted set of circumstances.Why haven't there been 10 or so books by prominent economists with titles like "markets are often over-rated"?

But perhaps the most important point he makes is that we shouldn't expect a "theory of everything" to emerge from efforts to go beyond the old conventional wisdom of market efficiency:

...one of the key messages we need to get across is that while good economics can help address specific problems and avoid specific risks, and can help us think through appropriate responses to continually changing problems, good economics is never going to provide the apparently certain, simple and complete answers which the pre-crisis conventional wisdom appeared to. But that message is itself valuable, because it will guard against the danger that in the future, as in the recent past, we sweep aside common sense worries about emerging risks with assurances that a theory proves that everything is OK.

That is indeed a very important message.

The speech goes on to touch on many other topics, all with a fresh and imaginative perspective. Abolish banks? That sounds fairly radical, but it's important to realise that things we take for granted aren't fixed in stone, and may well be the source of problems. And abolishing banks as we know them has been suggested before by prominent people:

Larry Kotlikoff indeed, echoing Irving Fisher, believes that a system of leveraged fractional reserve banks is so inherently unstable that we should abolish banks and instead extend credit to the economy via mutual loan funds, which are essentially banks with 100% equity capital requirements.8 For reasons I have set out elsewhere, I’m not convinced by that extremity of radicalism.9 ... But we do need to ensure that debates on capital and liquidity requirements address the fundamental issues rather than simply choices at the margin. And that requires
economic thinking which goes back to basics and which recognises the importance of specific evolved institutional structures (such as fractional reserve banking), rather than treating existing institutional structures either as neutral pass-throughs in economic models or as facts of life which cannot be changed.

 Amen.

The European debt crisis in a picture

From the New York Times (by way of Simon Johnson), a beautiful (and scary) picture of the various debt connections among European nations. (Best to right click and download and then open so you can easily zoom in and out as the picture is mighty big.)

My question is - what happens if the Euro does collapse? Do European nations have well-planned emergency measures to restore the Franc, Deutchmark, Lira and other European currencies quickly? Somehow I'm not feeling reassured.

Studies confirm: bankers are mostly non-human at the cellular level

This is no joke. Studies show that if you examine the genetic material of your typical banker, you'll find that only about 10% of it takes human form. The other 90% is much more slimy and has been proven to be of bacterial origin. That's 9 genes out of 10: bankers are mostly bacteria. Especially Lloyd Blankfein. This is all based on detailed state-of-the-art genetic science, as you can read in this new article in Nature.

OK, I am of course joking. The science shows that we're all like this, not only the bankers. Still, the title of this post is not false. It just leaves something out. Probably not unlike the sales documentation or presentations greasing the wheels of the infamous Goldman Sachs Abacus deals.