The Coder Behind the Mortgage Meltdown
axjms writes "New York Magazine has a confessional/abdication from the man who wrote the software that turns mortgages into bonds and those nasty little things called CMOs. An interesting first-person account from a coder whose work reached far beyond what he or anyone could have anticipated."
Because it is a fresh story with no comments.
Or... It was...
Until you re-redified it. Thanks.
Joe Public: What happen ?
Coder: Somebody set up us the bomb.
Operator: We get signal.
Joe Public: What !
Operator: Main screen turn on.
Joe Public: It's you !!
Wall Street Fat Cat: How are you gentlemen !!
Wall Street Fat Cat: All your base are belong to us.
There is no way in Hades that this topic could possibly be addressed honestly - not at NYMag, nor at
The underlying horror of the demographics at work here - and the galactic insanity of the CRA & the redlining initiatives & the fiduciary disaster at Fannie & Freddie - is just too much for the circuits to handle.
Not to mention - heck, even I can't mention that one.
This article from eight years ago sure did a great job of predicting this whole thing. Is it any surprise that when a government (whether under Clinton or Bush) promotes "affordable housing" as an end in itself, by manipulating interest rates and bank regulations, that they're bound to create a bubble, and bubbles by definition cannot last?
Makes my off by one errors seem so quaint. Add 12 zeros and soon you're talking about real money.
120 characters isn't enough to explain it.
The real reason is just generalizing the default rates from the small pools of subprime mortgages given to people who had background checks to big steaming piles of freshly-made subprime mortgages, given to whoever comes in the door...
Until you de-redified it. Thanks.
Fixed that for you
....I started world war II, even though I wasn't born yet. World war I. Me again. I messed up the decimal point. I hate that. I always do that. Oh and that devasting flu epedemic that killed more people than the war. me again. The rise of aids. I'm afraid that was my friend Jim. Excuse me please I have to go take my little red pills.
These posts express my own personal views, not those of my employer
Two words: Information asymmetry.
The end of the article starts to get to the heart of the problem, which really happened after he was involved. It was when they started doing this with all debt that it got really bad. And even then its only half the picture without looking at the other piece of this the Credit Default Swap. Another thing he alluded to when he talked about default models. The problem was much more complicated than this one guy.
Can you say scapegoat?
Of course, it's a geek who is to blame for it all with his immoral software witchery. It couldn't possibly be the result of a large number of greedy, thieving scum, who were regulated by greedy, corrupt scum, and they in turn were regulated by a greedy, corrupt government.
The writing was on the Wall(street) for the subprime meltdown for a very long time before this software was written. It was obvious to anyone with Economics 101, a long time ago.
Thank doo.
The summary makes it sound like it was all one person's fault. This can't possibly stand up to reason.
First of all, if the code was so important, it should have been reviewed, tested, etc. Bugs happen, everybody knows it. Finding and fixing the bugs before entering production is the responsibility of everyone involved in the whole process from specification to acceptance.
Secondly, even if there was an undiscovered bug in the code, that doesn't excuse those who relied on the faulty outcomes. The whole game in a free market is that the same thing has different values to different people. You must do your own calculations, based on your own inputs, using your own methods. If someone else messes up their calculations, that's your opportunity to win. Relying on someone else's numbers is a risk, and relying on them blindly is a recipe for failure.
All in all, yes, of course, if you wrote buggy software, you get the blame for that ... but it's not your fault that the bugs slip through the cracks and everybody ends up relying on your buggy software. That is their own choice.
Please correct me if I got my facts wrong.
It has nothing to do with # of comments. I see 0-comment green articles all the time. The red means that it's "in the future" and being seen by a subscriber. For some reason they've been showing up for a few seconds to normal users too.
The guy coded it. Who created his requirements?
Sig ?
FTFA: But when 1,000 similar loans are combined, and the U.S. government, through Freddie Mac and Fannie Mae, absorbs the default risk, you now have a nifty little AAA-rated piece of paper paying one or two points above Treasury bills.
It's real easy to gamble when you don't have to bare the risk. That was what caused the banks to make all those risky loans.
Yes but i've never once seen a red article with comments.
Bug:
Title: "Depression 2.0"
Type: "Suggestion"
Description: "This might not be a good idea"
Status: Unresolved
The idea that giving loans to THOSE PEOPLE (implicitly poor, black, and whatever other qualities our society is calling moral failings this week) is behind the collapse of the financial industry and had nothing whatsoever to do with the saintly finance industry's business practices itself is a meme that really needs to bite the dust. Was CRA part of the problem? Maybe, but there's no such thing as a single cause to a collective fuckup/fiscal meltdown of this magnitude. I'd argue that the repeal of Glass-Steagall is an even larger singular driver.
I'm sorry if it seems like I'm singling you out or jumping down your throat in particular, I'm just real tired of simplistic finger-pointing at the CRA. (I even vaguely recall seeing numbers that said CRA-driven loans were actually less likely than average to be in foreclosure, but it's been a good while and I can't remember where to dig up the particular citation.)
News for Geeks in Austin, TX
Subprime mortgages are precisely those mortgages that Fannie/Freddie WILL NOT buy and securitize. Rather, it was the large investment banks that bought and securitized these mortgages- sidestepping entirely the very 'government manipulated interest rates' that you point to as the genesis of the housing crisis.
Stop parroting the 'truthy' psuedo-information promulgated by the right wing and start growing a clue by looking things up.
Oh, yeah, right- this is slashdot. The place where Java died 10 years ago and everything is done in Ruby...
This is over a month old.. surely we can keep it a bit more fresh, right Slashdot?
arl with a k - a blog of mine.
That played a large part in this problem. I was eyeing a home from around 2000-2001. Proces were still reasonable. Then the rates dropped to ridiculous lows. Great, right? But then that caused a mad rush on homes, driving the prices to even more ridiculous highs. At that point, your monthly payment became even higher than when the interest rates were higher. At that point I dropped out of the market for a house. Who the hell else didn't see this coming? Who was Alan Greenspan really helping by keeping the rates so low?
A sentence you'll never see on an Internet discussion board: "You know what? You're right."
I worked for a financial structuring company about a decade ago. One of the things we specialized in was subprime default predictions. We were able to predict with frightening accuracy the number of loans (and which ones) in a portfolio that would default and helped companies structure portfolios around the expected defaults and cashflows.
Why is this whole fiasco not exactly a surprise? Well, no one was buying. Nobody _cared_ that the loans they were handing out would default. The company I worked for closed its doors.
The tools were available, but nobody used them. People were making bonuses off of the number of loans they sold, not the cashflow that was expected. They'd give loans to people who had no way in hell of being able to pay it back.
Assuming the guy's software was sound, greed is really the culprit in this case, not the software or the analysis...
correlation does not...awe forget it...
Wired: The Formula That Killed Wall Street
David X. Li formula used "Gaussian copula function" for risk estimation. It greatly oversimplified risk estimation and ignored any nonlinear, topological and whatever nontrivial dependencies, taking into account only single correlation parameter. Formula was applied recursively and the end result was completely divorced from reality.
oh good, my comments still there from the first time i saw the story:
i programmed in some of the same subject matter for several years recently, and much of this strikes me as a very believable tale. ...except it feels history-rewritten so as to remove any negative light from the author. he comes off entirely too saintly-while-surrounded-by-evil, and that makes me wonder what else to believe.
in particular how he made it seem like he just happened to fall into his deal to maintain/integrate/etc the software for its new owner, unpaid for a cut of its sales. that's a daring endeavor you take only when you honestly believe in long-term success, so i don't see "i'm tired and wanna take something easier", i see "all in, show your hands boys" kinda farm-betting. he knew then like he said now that his software could become the standard, shot for and achieved success. but i don't think his waxing philosophical about the potential dangers of that success started only after the trouble.
the contractors building the death star knew the risks of that association, so to speak. (I should explain, this is a meme, and honestly an unfair comparison)
http://www.mcclatchydc.com/251/story/53802.html
http://www.ptmortgage.com/blog/2008/10/01/pointing-fingers-was-it-cra-and-minority-lending-that-caused-the-mortgage-mess/
http://www.prospect.org/cs/articles?article=did_liberals_cause_the_subprime_crisis
http://www.frbsf.org/news/speeches/2008/0331.html
Finally, there's a summary at Wikipedia.
Tweet, tweet.
The ONLY reason mortgage brokers had more information was because the buyers didn't demand all the information the broker had.
It really is that simple.
They didn't do their due diligence on these investments themselves, they relied on a third party.
That third party (rating agencies) didn't do their due diligence on these investments either.
At the consumer level, we almost never inspect the investment details to any extent, mostly because so few even ask for the details that it isn't worth their while to bother preparing the information.
As far as the mortgage agreements, I didn't take mine to my lawyer as it was pretty straightforward. The problem with many of the subprime mortgage wasn't that the contract themselves were fraudulent, more that the people signing them didn't understand what the contract was at all. Which isn't surprising as most peoples financial literacy is absolutely horrible.
It is to alert the First Posters to get ready.
'The red means that it's "in the future" and being seen by a subscriber. For some reason they've been showing up for a few seconds to normal users too.'
That gives me a great idea! Why not devise some sort of complex financial instrument that nobody understands, which effectively bets the entire economy on the future colour of Slashdot articles? It would be no sillier than what happened over the last decade, and pretty easy to implement if we can come up with a single neat formula that seems to give correct predictions if you don't look too hard. Speaking of which, I thought we were still blaming this guy:
http://www.wired.com/techbiz/it/magazine/17-03/wp_quant?currentPage=all
The vast majority of WWII US servicemen did not see service on the pointy head of the spear. The ones that did serve at the pointy head got ground up, but there are not enough battle-scarred combat veterans to create the mass-PTSD problem that you posit. The overwhelming majority of veterans got bored out of their skulls for the duration (but nevertheless made a vital contribution to victory).
Your undisciplined post is fun to read, though.
the galactic insanity of the CRA
Whether the CRA was a good idea or not might be up for debate, but if "galactic insanity" implies that it was operating at a scale necessary to be a real driver of the crisis, there are significant indications you're wrong.
Consider, for starters, these statistics:
"Federal Reserve Board data show that:
* More than 84 percent of the subprime mortgages in 2006 were issued by private lending institutions...
* Only one of the top 25 subprime lenders in 2006 was directly subject to the housing law that's being lambasted by conservative critics."
There are a number of other relevant resources (such as those posted elsewhere in this discussion and in my comment history) which also examine the idea that the CRA was a significant cause of the current problems. The data seems to indicate that not only were CRA loans not any significant portion of problematic loans, they're actually turning out better than comparable private loans.
Tweet, tweet.
no, this sounds like "The plural of anecdote is not..." Yeah, forget it.
Is it sad that I am more likely to recognize you and your posts by your sig than your name or UID?
I don't understand the need (apparently in the article above) for people to blame everyone who had any connection at all to the financial crisis. This guy didn't do anything yet some of them are referring to him as a "scumbag" (and maybe a few naughty terms, I didn't look that hard). Further, Osinski claims to feel a little guilty, though he never explains why he should feel a shred of guilt. As I see it, he built a tool. Maybe highly leveraged traders leaned on that tool too much, but it's not intended to spot systemic risks (particularly the risk that all assets decline in a correlated way). Those systemic risks are what brought everything down. So a tool, working as intended, used by fools who made some hideously risky bets.
So, we all had a great laugh when it transpired that the greedy reckless banks had been caught in a predicament, namely having all those crappy mortgage backed securities on their own books, and we figured, serves them right. I guess we did not see that we would end up paying for them.
Who is really to blame for this:
(i) the guy taking out the large mortgage he knows he cannot afford, but knows he can walk away from it (well, in the US anyway)?
(ii) the mortgage salesweasel, selling products patently unsuitable, for his instant bonus?
(iii) maybe the big banks packaging up these bad mortgages, into bad maths products, sold as investments to people who may have trouble with long division, let alone comprehension of how to drill down into CDO squared?
(iv) the programmers who wrote the software to allow all this to happen?
Yeah, we know who is really to blame...
That's because you can't post comments to articles that are "in the future". One of the "benefits" of being a subscriber is being able to see the articles early, but you can't post to them until they go live (green) on the whole site.
Just wait...it gets way better:
http://monkeyspushingbuttons.com
He was part of a team that wrote some trading application. Confession? Is this a joke? Blaming wall street for this meltdown is like blaming your electrician when the power company stop providing power. All they do is repackage stuff. All the repackaging in the world wouldn't raise home ownership from 20% to 30% in 10 years. This was through policy... Brought to you by your friendly government (which I must be a right-wing nut for questioning, right?). Reminds of a the Jackie Mason joke: "This is the richest company in the history of the world and every year we lose money. That's because your congressman gets paid whether we lose money or not. I say put em on commission..." Honestly though... It's the "ownership society" that created this crisis -- not the middleman they are trying to blame now.
Any guest worker system is indistinguishable from indentured servitude.
Ah, Slashdot: where not even your made-up, bullshit words are safe from the grammar Nazis.
Forgive my negative response, but I'm afraid P(etroleum)B(roadcasting)S(system) got it wrong, but is still propagandizing correctly. The problem was indeed the securitization of mortgages - which created an enormous number of hyper-leveraged financial products, from one original and often shaky financial instrument - thus incredibly increasing the amounts brokers, and banks and investment houses, and insurance companies (and combinations of all three institutions) earned, again and again and again. The entire point of Credit Default Swaps (CDS) and credit derivatives is super-leveraging while compounding risk to infinity. The problem is the credit derivative - and its various subcategories - which create super- and ultra-leveraging - which allows for a small number to illegitimately become billionaires at the expense of the rest of us - because that super-leveraging then becomes super- and ultr-deleveraging!
It doesn't matter whether or not you can understand it, what matters is that it occurs - there is a colossal transfer of wealth - and the rest of us honest types are royally screwed!
Don't blame the coder. The mortgage meltdown was a "perfect storm" with lots of causes all coming due at the same time. It was a systemic problem. Unfortunately, our "solutions" aren't getting at the root causes, just covering them up with lots of cash. The next crash will be worse because of it.
Don't blame me, I didn't vote for either of them!
Yeah right. They always blame IT.
There are some really really bad jokes that could be made of the function name. Only problem is that nobody on Slashdot has been outside the basement long enough to get them.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
This is what $2 million of bonus can do to grown men.
I wanted desperately to try to argue that perhaps the kind of person who can position himself to make that kind of money is simply the kind of person who would be amenable to literal pissing contests and so on, rather than money itself changing what were previously normal people.
I've never had a problem posting to them... or seeing them... and I'm not a subscriber.
Obviously the guy who wrote this article is not a programmer, he is a liberal arts major and knows a little about the crisis... nice interesting read.
I did not like the fact that he claimed that he was over paid all along his career, and compared the work done by some oyster farmer to being harder than a computer programmer, sounded more like a pol-pot fan.
Subscribers don't just see them for a few seconds, they see them sometimes for hours. The issue with non-subscribers seeing them for a few seconds or minutes appears to be a bug.
Is that you?
they could have at least had a beta testing phase before they went live and brought down the whole financial system.
So not only are they crap at economics, they are crap coders too.
Meh.
Because you can charge high-risk individuals higher interest. So loaning to high-risk individuals can be extraordinarily profitable, if you can figure out a way to average out the risk.
This isn't rocket science--unless you get all of your "information" from right-wing talk radio.
So we go back and kill Carl Gauss. Then my CRTs won't be all ghosty and my house would still be worth something.
I like music
Whatever it is, it's confusing. Can we at least get a link to a FAQ near the "green" button in the upper right corner?
So being a subscriber allows you access to a time machine? Thats pretty cool.
I'm interested to know what you think freedom is.
Shop as usual. And avoid panic buying.
I disagree with you on several fronts.
First, I find it interesting that you seem to think that a computer programmer cannot also write for a non-technical audience.
Second, I think I'm probably overpaid, and I *know* (having done both) that being a tree planter is harder than being a computer programmer.
For a good first person background on how Salomon Brothers and other institutions developed and popularized CMOs, read Liar's Poker by Michael Lewis.
How is this a troll? The guy's (I'm assuming it is a guy here) horny. Let's help a brother out! I suggest craigslist erotic services page, or perhaps http://www.pornhub.com/ for some great vids if you don't wanna pay for a hooker.
Um, dude, RTFA. It's a piece by a software developer who wrote a bunch of software for mortgage securitization, telling his story and doing some navel-gazing about whether he should feel guilty about his part in the debacle.
Are you adequate?
The article isn't seriously claiming that one guy was responsible for it, nor that it was due to a software bug. The article was written by a guy who developed some mortgage securitization software, who tells his story and idly asks himself to what extent he shares responsibility for the debacle.
Are you adequate?
All these bubbles can be laid at the feet of easy credit. And it starts with a credit based money supply scheme, rather tha a past produced wealth money supply system. For millenia, money was actual wealth, or a tangible and portable representation of wealth, wealth that had been produced, past tense. Now nations use a future credit system that inflates the money supply way beyond what actual wealth production would indicate as being sane, thinking that in the future, enough wealth creation will be done to cover that inflation. It is "loaned into existence". About as crazy a notion as it gets. They never get it right, no matter how much they try, and always eventually overly inflate, as they did with these mortgages then the derivatives of the mortgages and the sliced and diced risk contracts, which are bets on inflated wishful thinking once you distill it down. This leads to a series of boom and bust cycles that are more intense than they would have been if the supply really represented past produced wealth. Because you can't loan that which doesn't exist unless you inflate the system and base your figures on wishful thinking. That's all currencies are "backed" with now, a few fatcats ideas and some wishful thinking.
Although, it will still cost them far less than the American Empire they've been supporting for 60 years. And for some reason, I don't suspect the nightly news will mention it. Strange.
America's a wacky place. Spending less than 100 billion saving people who were dumb with mortgages is cause for Panic! Hyperbole about Socialism! Quick, throw a tea party! Fox News anchors weeping on air for their fallen values system!
Spending 1,000 billion on warfare every year is Patriotic! Go team! USA! USA! USA! Post some videos about shock and awe! Let's run some swell pieces on brand new weapons systems designed specifically to "protect freedom," and never mention their price tag...
..bad lending was removed...cause I can always get the house back so, so what.. But when bankruptcy would mean that you KEEP you HOUSE, well the lender won't lend you money unless they are pretty darn sure you will actually pay.
Killing bankruptcy housing protection was the last nail that let the combined bank-insurance-security industry rape and kill the plant - for money.
Interest rates pushed housing prices up, no doubt. But two simple rules would have prevented the bubble from getting catastrophic.
1) Leave Glass-Steagall in place (it was repealed in 1999). Banks are banks, insurance companies are insurance companies, investment firms are investment firms. Whining about losing "profit opportunities" are ignored, and intra/intercompany shenanigans greatly reduced. From 1987, defending the Act:
Securities activities can be risky, leading to enormous losses. Such losses could threaten the integrity of deposits. In turn, the Government insures deposits and could be required to pay large sums if depository institutions were to collapse as the result of securities losses.
2) Force companies that lend to keep the mortgage, without any side bets or leverages, until it is paid off.
And, if you really want to stop these cycles from developing, you have to implement usury laws once again, to prevent continued capital flood into financial services. No one is going to build a factory until it offers a competitive ROI.
taking into account only single correlation parameter
That's a single correlation parameter per pair of mortgages. If you have N mortgages then that's N^2/2 parameters.
This is one reason why people can't agree on a price for the CDO's. No-one can agree on the underlying correlation matrix.
[Intentionally left blank]
The oddest thing about Osinski's article is his claim to be "the one" to have written the CDO packaging software that brought down Wall Street-
That statement alone pegged my bogometer. Sweeping claims for sole ownership of a *type* of system that developed by many banks - bullshit.
During the 80s and 90s, I worked for several major Wall St. IBs, writing institution-level portfolio risk-valuation software - dealing with billions in net value across markets, trillions in notional face value (whoop-t-do.) And I collaborated with coworkers who wrote and maintained, get this, CDO packaging/securitization systems.
Osinski, wherever he was at the time, wasn't "the one." Many people worked at this, across numerous banks (eventually.) That he has a guilt complex about it is kind of absurd. He might have been an early developer, though certainly not the only one, and he was most definitely not the inventor of mortgage-backed bonds. That alone should clear his conscience.
His guilt is either misplaced, or amplified to a level that runs way, waaay outside his actual responsibilities as a developer.
Also, his claim that the code became "the standard" used by IBs around the world seems utterly bogus. At the firms I was employed by (and consulted for), while we did license code and contract out for systems developed by quant software boutiques for specific needs, things like securitization systems were in-house. Because: a) it was very complex, b) it had to be very specifically tailored to your "inventory" systems (and the retail banks you bought from), and c) at the time, you did not want an outside firm getting into your books or onto your network. (This was in the days before FIX became a standard.)
So, maybe this guy is seeing a second/third career as a writer. Good luck with that.
O lord, bless this thy holy hand grenade, that with it thou mayest blow thine enemies to tiny bits, in thy mercy.
Apparently a lot of people do not know what they are talking about. The people most invested in the system cannot see the flaws and do not want to. The financial jargon is used to obfuscate. Some genius that actually understands it all at the byte and master accounts level, made it very simple for everyone to understand.
Derivatives = Bets
Credit Default Swaps = insurance on bets
Hedge Funds = borrowing of money to gamble with (unregulated and secret also used to manipulate markets)
Taxpayer Bailout = Taxpayers covering the gambling losses for gamblers? (it won't happen without a revolution taking place to correct it)
Reality = Insurance (e.g. AIG) cannot cover failed bets which amount to: USD 206k per person-on-planet.
The number it is based on has grown from USD 1.144 Quadrillion to USD 1.405 Quadrillion, ie, +22% worldwide. The GDP of the entire world is USD 50 trillion. The derivatives "bets" total USD 1,144 trillion which is 22 times the GDP of the whole world. The money 1,144 trillion doesn't really exist in system but only in the terms of a contract, artificial value not validated by economic system participants. It would be inappropriate for the citizens to go into debt as they already have, to cover these contracts. The people that created this catastrophe do not feel the pain of their decisions, but the common folk do. You can read all the rest of this and a bunch more insight into a system that would actually work on http://coinage.me/ Perhaps most ironic was an attempt to build a computer game based on the current economic model, eventually the game / economy always crashed.
But we can't blame him either. He TRIED to warn the managers who could actually change course that there were serious limitations to the formula but they didn't want to hear it.
History has proven nothing but perpetual inflation, because inflation is the driving force of the economy. Yes, today, the average house price may be down by 30%. But in 10, 20 or 30 years, one may have to pay $1000/hour just to paint the house. The peak price of your house a few years ago may look a like a bargain 20 years from now. Remember, an average worker got dollar a day in the past. Rent would be like $30000/month. The problem is that you will likely still be live by then but too weak to work, and housing is a major cost still.
It all comes down to timing and cash flow of your investment.
Yep, that was one of the really bad jokes. Jokes like that must be why you're still in your mom's basement, huh?
The coder only codes the math the BA gives him/her.
Moral hazard.
"The best we can hope for concerning the people at large is that they be properly armed." - Alexander Hamilton
Actually, the question now would be
"How many fools will it take before the elders let natural selection takes it's course"?
While I am for charity... Charity is not the answer to everything.
Also charity should not replace good ethics, morals and that sense of accompishment.
If income tax amounted to a charitable 10% of my income for social, economic and the nations well being then take it... But as it stands now 50+% is not charity, it's robbery, and this is the problem.
Thanks. Stand up and take credit for being an enabler of the elite economic ruling class to drive our nation into the ditch.
The problem is that clever banks like Lehman Brothers (RIP) took those debts and spread the risk by nefarious, unregulated means.
If somebody had stopped the securitization of bad mortgages the problem would have stopped with the banks making bad loans and their costumers. As things were these securities eventually led to such distrust in the interbanking lending system that credit literally stopped worldwide.
We could have bad mortgages as long as corporate banking had been moderately risk averse...
IANAL but write like a drunk one.
... when you buy you are left with two very valuable assets at the end of the mortgage: the house and the usage you got out of it.
If you treay a house like your home then you don;t care if its price rises or falls, at the end, the day after the mortgage is paid, you begin to make money (either by not paying rent or by renting the house out and pocketing most of what you charge).
If you are renting, after the same period of time you are left with, er.. nothing, and better you pay your rent next month, otherwise you will be thrown out.
IANAL but write like a drunk one.
If all had been banks not getting paid, they would have got the houses, would have lost a bit of money (or a lot, that is irrelevant) and that would have been the end of it (not really, it would have affected the economy, but would not have provoked a worldwide meltdown).
The problem is that investment banks, thanks to lax regulation, decided that packaging those bad loans in crazy quasi ponzy schemes was a good idea.
And the people measuring risk (rating agencies) did not to their work.
Bad mortgages would have not come close to cause such monumental problem, no matter which way you want to look at the mess we are living through.
IANAL but write like a drunk one.
It is all very basic maths, and nowadays the Intarweb has calculators for you so you know exactly how much you need to pay each month.
I worked myself out this, compared the monthly payments for different mortgages against my salary, and chose one that I could afford (the mortgages brokers I talked to didn't offer the one I chose BTW, what a surprise).
4 years later I am perfectly fine, in spite of having being unemployed for more than a year.
IANAL but write like a drunk one.
Self-indulgent garbage.
That is all.
"Formula was applied recursively and the end result was completely divorced from reality."
"Working as intended", I am sure, would be the honest answer for the vast majority of people who are still spending the money they made off this.
When the only tool you have is a claw hammer every problem starts to look like the back of someone's skull.
CMOs are all about expectation of prepaying mortgages and the correlation of that with interest rates. Intex is based on historical data, which actually takes into account the FICO scores and ZIP codes associated with individual loans. David Li's work involved correlation between the default of corporate bonds and other securities. These are apples and oranges.