Economics and similar, for the sleep-deprived
A subtle change has been made to the comments links, so they no longer pop up. Does this in any way help with the problem about comments not appearing on permalinked posts, readers?
Update: seemingly not
Update: Oh yeah!
Saturday, February 28, 2009
Iran's nuclear reactor
Apparently they're starting the final round of tests. So far, it is 34 years behind schedule and approximately 12 times over budget. I think they may have taken some tips from the British nuclear power industry.
this item posted by the management 2/28/2009 12:27:00 PM
Wednesday, February 18, 2009
Capital Decimation Partners: slight return
OK, wife and kids are off at the seaside, a couple of gin and tonics in the back of the neck … let's talk three thousand words of medium to high-end financial economics. General interest readers are excused this one, although I don't intend to bring out the "Math Cock" (a mythical organ possessed by graduates of Warwick University and Imperial College, which is ritually drawn out and slapped on the table whenever they appear to be losing an argument about economics) too much and it ought to be possible to follow along with a bit of help from google. Read the footnotes last rather than as you go along, since most of them are tangentially related rants on personal hobby horses of modern finance.
Basically, hedge fund performance measurement, and specifically the question of how to distinguish between genuine investment talent on the one hand, and put-writing strategies (the familiar "Capital Decimation Partners") on the other. How would I go about choosing a hedge fund (specifically, let's make this concrete and say a long/short equities fund; presume that all references to "hedge fund" in this post are so), if I were rich enough to be in the position to choose? Difficult question; let's start with a few building blocks.
Building block 1: Capital Decimation Partners. Basically, Andrew Lo suggested, in a couple of papers and in his book on hedge funds, that one could match up a few of the stylised facts about hedge fund performance over the last ten years, to an unsophisticated strategy of writing puts on the SP500 index, thus showing that in short runs of data which did not contain a major market crash, it was impossible to distinguish between genuine talent, and simply being structurally short volatility and creating a position that earned seemingly abnormal returns in low-volatility periods, which were merely the reward for bearing the risk of crashes. This view got picked up by the Taleb fans and index fund cultists, who are always on the lookout for another way of arguing that people richer than themselves are charlatans and dupes, without necessarily much understanding of Lo's actual point (as discussed in the linked post above). One thing that's in Lo's book which people don't talk about anything like as much is the fact that he also gave the example of "Capital Decimation Partners II", which didn't simply write puts; it carried out a trading strategy in cash equities which replicated the payoffs from a written put, using the Black-Scholes equation to act as if it were delta-hedging a long put position. This brings me on to:
Building block 2: Options are financial services. Another thing falling into the category "jolly useful things I learned at London Business School". Anthony Neuberger's options & futures class drummed this into you - the derivatives market is essentially a financial services market, where you hire someone else to carry out a trading strategy on your behalf, on the assumption that they have economies of scale in doing so. This is most obvious in the case of portfolio insurance, where one literally hires a trading firm to execute what amounts to a massive stop-loss order, but it's of utterly general application; every derivatives payoff structure defines a trading strategy. Often if you're confused by a security, it's worth thinking about what kind of trades you would execute if you were replicating it.
So, as I said, if you think about the trades you'd execute if you were replicating a call option, it's easy to see what you're doing - you're selling securities for cash as the price falls (eventually going to 100% cash as time goes on if the option is out of the money), and buying securities as the price rises. In other words, what you're doing is similar to the execution of a stop-loss - you are "cutting your losses and letting your winnings ride". On the other hand, if you think about how you'd replicate a written put (or the Capital Decimation Partners II trading strategy, same thing), you would sell securities as the price rose, and buy when the price fell. You would be "buying dips and selling rallies".
The beginnings of a clue: If we think about the options in payoff terms, a long call option is equivalent to buying insurance, and a written put is equivalent to selling insurance. If we think about them in trading terms, however, a long call is like a stop-loss, while a short put is like … well, who in the market is a structural buyer when the world is selling, and a structural seller when the world is buying? Answer - among other people, the market-maker, specialist or equivalent liquidity provider. Someone who's providing liquidity to the market more or less has to do this, or they're not providing liquidity. And this gives the first hint of a clue, because it does suggest that not all "Capital Decimation Partners" are mugs, no matter what Nassim Nicholas Taleb thinks. As anyone with even a passing knowledge of the market knows, specialists tend to make a ton. Which implies that if you have even quite a small information advantage (say, a specialist's knowledge of the order book), investment strategies which can be seen as having a high-level similarity to structural synthetic written puts, can be very good news indeed.
But, but but … a specialist doesn't just sit tight and provide liquidity! He uses his information! Yes, just a second, I need to do a little model first.
A little model. Say there's a security which has the true value V, and you (because you're that good) have a private and wholly reliable signal which tells you V with certainty. For the time being (and this is important), V is a constant. Say also that V trades in a market which is "efficient" in the Fisher Black sense - the price P fluctuates widely, but is always between 50% and 200% of the true value. You've got the job of trading V for Capital Augmentation Partners. And you're managing my money, so get it bloody right. What is any model of your optimal trading strategy going to be like?
Well, let's put the math cock back in the math pants, and just think about qualitatively how you're going to use your signal. Obviously you're going to be long when P/V <1 and short when P/V>1. And similarly, because you want to profit from volatility and deploy your capital optimally, your maximum long position will be achieved when P/V ~=0.5 and your maximum short position will be when P/V ~=2.
In other words, for an informed trader in a market where the true value of the security is reasonably stable, "buying dips and selling rallies" is almost always going to be the right thing to do. And this is the strategy which is bound to show up on any statistical test (including Lo's own proposed measure) as being equivalent to a put-writing strategy, or Capital Decimation Partners. The point that I want to make here is that if you've got a good actuarial estimate of the risks, writing insurance is the right thing to do - a good trader will very likely give a false positive on any measure which is meant to distinguish "genuine" talent from "mere" put-writing.
So what happens if fair value is variable. The thing that will sort the sheep from the goats, however, is what happens when V changes. Say there's a sudden stepwise change in V, so that it moves to a tenth of its previous value. On reasonable assumptions about the stochastic process for P, P is going to start moving downwards. But this time, you really don't want to be buying this dip, because it's not a "dip", it's a shift down to V'=0.1V, and if you follow your old strategy of going all in at 0.5V, then you're going to lose your shirt. And now I can cash the cheque I wrote a couple of paragraphs ago in talking about market-makers - the skill of running a specialist book is entirely in realising when "normal" provision of liquidity has become a dangerous game, and when the price needs to be marked up or down to a new level.
In fact, this isn't just the skill of being a market-maker - it's a hell of a lot of the whole skill of investing. The technical analysts will tell you, if you stop sneering and making hilarious jokes about astrology long enough to let them, that securities tend to spend about two-thirds of their time in trading ranges and one-third of their time in trends. Which would be consistent with a wide variety of sensible market microstructure models under which true value changed slowly, and as a result to specific and infrequent events (say, because it was determined by economic processes which shifted regimes as a result of historic, nonergodic processes). Investment talent of the sort that you want to look for in a hedge fund manager, resides in being able to know, ahead of the rest of the market, when underlying value is going to change, and to adapt trading structure accordingly.
A somewhat overcomplicated estimator for talent. So basically, a really excellent fund manager would have the characteristic that changes in his trading strategy anticipated changes in V. Investment in this view is a problem of forecasting structural breaks or regime changes. So if I had unlimited resources of data and mathematical ability, I would take data on securities prices, and on the trading positions of the fund under analysis. I would use a STOPBREAK (stochastic permanent breaks) model to identify regime changes in both, giving me a vector of dated regime-changes in the equity returns series, and a vector of dated regime-changes in the trading strategy series. I'd then use the normal toolkit to estimate the lead-lag relationship between the two series. Obviously a lead of the trading strategy series over the returns breaks series would be ideal, but a short lag would also be worth knowing about - while the man who can tell you when a big change is coming is a gem of great price to be treasured, the man who can spot when something's going wrong and stop losing, is also a highly useful lad to have around, and perhaps a bit more realistic to hope for. So that's what I'd do if I were in the manager research game.
A less complicated and perhaps more sensible estimator: This is a bit of a sledgehammer to crack a nut approach though. I would guess (and could probably prove if I had three weeks spare time and masochism to devote to relearning a load of stochastic processes again) that a reasonably good robust non-parametric estimator for the lead-lag based talent measure suggested above, would be the number of >10% drawdowns, which is a statistic that lots of funds will put in their risk disclosures anyway. I'd specifically divide the average return per year, by the average number of drawdowns per year, and give myself a measure of how much return these guys made per "mistake". I'd then take a look at >20% drawdowns and see whether they were prone to making big mistakes. 
So there you go. I almost feel like a disquisition on David Hume's theory of causation now (in that the skill I'm talking about is that of identifying when a past regularity is no longer reliable), but this is almost certainly the gin talking. Be careful out there people - whether you're trading stocks or fighting land wars in Asia, the race may be to the swift, the battle to the strong, but long term survival goes to he who identifies stop loss points ahead of time and sticks to them.
 I am using "investment talent" here in contexts where lots of people say "alpha". "Alpha" is a technical financial term for "I don't know what I'm talking about, even if I do have a CFA after my name". People who believe in the literal truth of the one-period CAPM can convince themselves that investment outperformance of a risk-adjusted index is generated by a linear factor which enters into the securities market equation as a simple premium to the market-beta rate of return. This is a false belief which is frighteningly resistant to evidence. Alpha doesn't work as a measure of market-timing ability, for example - someone whose portfolio has a beta of 1 when the market's going up and 0 when it's going down, can in some circumstances be estimated as having negative alpha (basically if he uses his magical abilities to achieve a market rate of return with lower volatility, which is quite plausible, he will show up as having subpar alpha because of his seemingly high correlation with the market - he only makes money when everyone is making money, and the typical CAPM equation won't give him enough credit for not losing money when everyone else does). The use of "alpha" to mean "outperformance", like the use of "tail events to mean "crashes", is a piece of jargon in the most pernicious sense possible - it gives the impression of understanding things at a deeper level, while actually committing you to a theory which is badly misleading about important cases. "Beta" as a measure of market factor risk is not on much better ground.
 Taleb tends to get cross with people who point out that in general, buyers of options lose money and sellers of options make money. At various points in "Fooled By Randomness" (less so in "The Black Swan"), he gets quite close to arguing that in sufficiently long runs of data, the opposite will be the case (and as I noted in my first CDP post, this is trivially true as a statement of actuarial science, because if long call/short put is equivalent to buyer/writer of insurance, and it is, then since the probability of ruin for an insurer with finite capital is 1, in finite time, there is a sense in which in the long run, all the capital has to go from the sellers to the buyers of insurance. But this is self-evidently not an economically interesting sense). In the real world, though, a specialist on the NYSE, particularly under the old regulations, was a structural writer of put options with a small but significant information advantage, and the position of NYSE specialist was a notoriously lucrative one, handed down from father to son like a taxi badge.
 Perhaps at this point one might wonder if there is a short way here - to gain the advantages of the synthetic put strategy, while building in a rigorous discipline of using stop-loss orders. An attractive thought, but I think no dice. A "buy dips and sell rallies" strategy combined with a stop-loss discipline - well, convert it back into options language. Here you'd have a written put, combined with a bought put at a lower strike price. In other words, what I would call a "collar" and Bernard Madoff apparently called "a split-strike conversion strategy". What you've got here is a strategy with the intrinsic leverage of the put-writing strategy, but limited downside in the event of a real crash, and in exchange for that downside protection, you've effectively paid a fixed cost element equal to the call premium. So you've got financial leverage and a fixed cost, which suggests that if you're doing this, you had better be really sure that you're right in your estimate of V, and in your estimate of the volatility of P (which would determine the level of P/V at which you placed your stop loss). If you get this last parameter right, you've achieved what you wanted to, but if you get it wrong, then you're going to get repeatedly stopped out, which will kill your overall returns.
 Oh yes indeed. As I note above, trading collars really does separate the men from the boys - it's probably more or less equivalent to the actual behaviour of a skilled specialist, and notoriously it's a very leveraged market; yet another way to look at it is that you're trading calls, which is intrinsically leveraged, but doing so for less premium because of the options you're writing, which allows you to achieve even more leverage. If you've got talent trading collars, you're going to make a hell of a lot of money, but if you haven't, you're gonna find out really fast. This, by the way, is how Harry Markopolos really spotted that Madoff was a con artist from the returns series - it's a bit unclear in his SEC testimony but basically the Madoff fund returns looked nothing like a collars-trading set of returns - you can make good money trading collars, but you can't make it in the smooth way that Madoff claimed.
 I would then, having done this, give up on the temptation to create single indicators. The approach I've outlined here would, I think, do pretty well in measuring the performance of long/short, high turnover funds. But it would keep you out of more or less every biotech fund in the world, for example - people who are shooting for ten-baggers in smallcap tech stocks are going to have to tolerate lots of drawdowns on the way up of the sort that I would view as a "mistake" if it happened in the context of an active trading strategy. And although I haven't checked, I would guess that people who did in fact generate their outperformance through something similar to Sharpe's alpha (picking securities with a single, constant, small premium to the market return), would show up as having so-so performance on this screen. There is, basically, no substitute for understanding what you're talking about in both a statistical and a fundamental sense, which was the subject of my Christmas address.
this item posted by the management 2/18/2009 03:56:00 PM
Confidential to MY
Do you really want to go there? It wasn't so long ago, you know.
One doesn't want to be too mean about Grameen, because their heart is in the right place, (albeit their bank is in a very different place on the Bangladeshi income scale than it used to be pre- the massive restructuring in 2001, a fact which is not always made clear in publicity material). But they really do have a strong habit of overselling their projects. Sobi Rani, the woman quoted in the article "'gets' the basis of successful banking". How much does she get it? She sells yoghurt door to door, that's how much she gets the basis of successful banking. Well, she doesn't actually sell yoghurt any more because the yoghurt didn't taste very nice, but there's a profitable Grameen yoghurt business now and she's involved in it. Well, maybe it's not profitable, but it's been redesigned and it's going to be all over the country! Well, it might not get distribution right away, but they're still growing and opening up factories. Well, they're not actually opening up any more factories, but if the sales get better and they solve all the problems and make a profit, then they might. But at least it's Bangladeshi people helping themselves. Well, Danone is doing most of the managing at the moment, but anyway, the point is, ADVANTAGE: GRAMEEN! In your face, capitalism and foreign aid! Microfinance rules!
I mean, give me a break here. After 33 years since Grameen was set up, Bangladesh is still a desperately poor country. The time for pretending that you had a silver bullet is long gone. Microfinance schemes probably have a role in the world, but it doesn't seem obvious at all to me that the planning of aid and development in Bangladesh ought to be built round the marketing material of one particular organisation.
In memoriam Daniel Pearl, by the way, who died seven years and just under three weeks ago.
this item posted by the management 2/18/2009 09:43:00 AM
Wednesday, February 11, 2009
Israeli election punditry
Well, it's not clear what it all means, or who's going to form a coalition with whom. Is Netanyahu right to say that it's a "victory of the right-wing bloc" or is Livni right that the winner was the party who got the most seats? I dunno. But I think we can see loud and clear from the results that the electorate of Israel has made one decision unambiguously. The Gil pensioners' party went from seven seats to zero. Israel has spoken, and the message is "fuck off, Grandad". I suspect that the problem was that there were never any moderate pensioners, prepared to condemn the excessive nagging and Werthers' Original consumption of the extremists. For the time being, though, pensionerism, however, has been confined to the dustbin of failed ideologies.
Update: corrected something that I thought was a synonym but isn't.
Labels: geopolitical trends that don't get into the newspapers
this item posted by the management 2/11/2009 03:34:00 PM
Tuesday, February 10, 2009
Idea for a panel show; Mrs Merton meets Question Time
Episode 1: So, Clive Crook of the Economist and Financial Times, what do you think about the practice of organising a claque and stroking its prejudices?
this item posted by the management 2/10/2009 01:15:00 PM
Monday, February 09, 2009
I still think that this could be the defining case of Alan Dershowitz's career
... an Islamist rebel group that has fired rockets into the capital city. No country on earth could tolerate this. They hide in an urban area, shielding themselves behind civilians. This is a war crime, and the consequences of attack are wholly the responsibility of the terrorists! Attack!
Should the man responsible be charged with war crimes?
I've noted this in the past; Dershowitz is a leading light of the USA Darfur campaign, but many of the legal concepts he's invented over the last few years (particularly that of the "continuum of civilianity") would be very useful to the other side if they could be made to stand up in court. The cases of Claus von Bulow and OJ Simpson both reveal that Dershowitz isn't scared of helping an unpopular defendant, so shouldn't Omar al-Bashir (whose indictment at the ICC is about to be filed unless there is some last-minute political compromise) be at least having his people talk to Alan's people?
I jest, of course I jest. But there's a serious point here. First, that it's a lot easier to maintain the good old moral clarity if you're not tempted to make apologetics for particular states that you like (at one point on Normblog, there were quite literally consecutive posts condemning the SA's attack on Muhajiriya as an atrocity, and taking a very different line on Gaza). Or to put it another way, the view that it's wrong to hold one country to a different standard than another ought to be honoured in the observance, not the breach. People like Bashir do certainly pay attention to all the fiddles and compromises made with international law in order to fold it round the contours of what we want to happen in the Middle East.
this item posted by the management 2/09/2009 08:09:00 AM
This is, as far as I'm aware, the second time in twelve years that my article "Remuneration and Risk" has been cited. I wasn't actually a "senior economist" in 1997 - I was a Trainee Bank Officer (Graduate), which was at the time the second lowest grade in the Bank's pay structure. (The following year they changed the grades and put the graduates on the bottom rung of the Bank Official grade, which means that the record I set for paid overtime will never be broken). Also, the BoE did not typically consider you to be an "economist" if you had a PPE degree from Oxford, basically due to bigotry on the part of the Warwick clique in the Monetary Analysis division (well come on guys, you know it's true) and I hadn't done my Masters by then.
But otherwise the FT piece is spot on; we published this article post-Barings as a shot across the bows of the industry, and everyone ignored it. The financial correspondent of the Telegraph referred to it as "hitting the market with all the impact of a feather coming to rest on a blancmange", an insult which has rankled ever since.
Labels: narcissism, nostalgia
this item posted by the management 2/09/2009 06:20:00 AM
Thursday, February 05, 2009
Moral Hazard: A parable
I'm still not talking about the crisis; specifically I'm not talking about all these plans which, at this late date, are still banging on about "moral hazard" and "the need to bail in private creditors" and so on. But I can tell stories:
I once knew a guy who trained martial arts, a lot. He had a proverb he was fond of. He used to say "Pain is just the sensation of weakness leaving the body". And so he kept on training, even when it really hurt, because he knew it was just weakness leaving his body. And it worked; over a period of twenty years, nearly all the weakness left his body. When I last saw him, there wasn't enough weakness left in his knees or ankles for them to even bend. He walks with a stick, of course. Turns out that you probably ought to leave a bit of weakness in there.
All right, let's look at it another way. Once, the Guardian Notes & Queries column had a question in it, asking what the economic consequences would be if suddenly God stepped in and made us all honest, and made it so we all knew that we were all honest. The idea was that it would quickly result in economic collapse; between security guards, ticket inspectors, makers of Tensator queue management equipment, some ungodly part of a modern economy is based on people being employed to check up on one another. It was quite a good laugh as a thought experiment about an economy exposed to a sudden technology shock.
But of course, the world would get used to it, and a new economy would grow up based on our universal trust, and one with a much higher average standard of living, since basically unproductive labour would be replaced by the production of goods and services. What would happen to such an economy if the devil came in and reintroduced dishonesty? Absolute collapse, surely; vast amounts of previously productive effort would have to be diverted once more to constantly checking that relationships which had previously been implicitly recognised to be completely free of risk were actually valid and that every single party to a transaction could be relied upon to meet their obligations. If you had a system of relationships based on more or less unquestioning trust, and then you broke that trust, how on earth could you expect the system to function again until the basis of that trust was somehow replaced?
Anyway, I'm just saying.
this item posted by the management 2/05/2009 12:16:00 PM
Wednesday, February 04, 2009
Pushback! Featuring Anthony Wells
Anthony comments on my Guardian piece about the BNP - he thinks it's a lot closer and more volatile than I do. I now have about fifty quid riding on this with various bets, so I'm not taking any more.
this item posted by the management 2/04/2009 06:38:00 AM
Tuesday, February 03, 2009
Republican is the new punk rock? Yes, that's about right
By which I mean, punk is dead and so is movement conservatism. Seriously, what is it with rightwingers trying to identify themselves with "punks" and their opponenents with "hippies"? Why would anyone want to do this to themselves?
Look around you at the world of popular culture. There are still lots and lots of surviving subcultures which are recognisably "hippy". There are next to none which are recognisably "punk". The hippies managed to cope with the rise in popularity of electronic dance music (which punk rockers rather spectacularly didn't). They inserted a lot of their main political issues and ersatz spirituality right into the mainstream. They even saved the fucking whale.
What happened to punks? Not a lot. Thrash metal, Green Day and that's about it basically. The only punk band that had any sort of longevity was the Cure. Michael Gove should be saying that the Tory Party are truly Goths at heart.
That is a strange one, by the way. If you'd been hanging around doing Paul Morley's job in say 1985, and you had to pick one out of New Romantic, Two-tone, Goth and glam metal to still be alive and relevant in 2009, who the hell would have picked Goth?
Update: Actually, while we're on the subject, now that five years' passing has somewhat diminished the emotional impact of the "Hurt" video, can we get a bit of reality with respect to Johnny Cash please? The simple fact that Rick Rubin says someone's cool does not actually make it the case. Cash made a small number of good country records (a very small number, and even "Live at San Quentin" has a hell of a lot of filler on it), and five or six very good tracks, spread across three albums, toward the end of his life. But he spent most of his career producing a vast amount of rubbish, of which this is entirely typical. Even the famous early country albums are country and western, not rock and roll and certainly not punk rock - if you don't like cowboy songs, you'll hate them. It's heretical to say it, but there was a most unimaginable amount of shit produced in Nashville between 1955 and 1958, much greater than the volume of execrable house music produced between 1988 and 1991.
this item posted by the management 2/03/2009 01:29:00 AM