KEY POINTS:
In this article, the business editors of The Independent (UK) throw some light on the crisis afflicting global financial markets this past week.
What is going on in the debt market and why should I care?
The debt market is what makes the financial world go round, providing credit for governments and companies to invest and individuals to buy houses, start up businesses and fund their education.
The market has become more complex as investment banks dreamt up new investment products based on these loans, which investors lapped up in search of high returns.
After years of relaxed lending, the market has suddenly seized up, triggered by rising defaults by "sub-prime" US mortgage borrowers.
As these defaults mounted, institutions rethought their attitude to risk and suddenly became scared of losing money.
Banks became unwilling to lend to each other for fear of not getting their money back.
The panic has spread to shares, and there are fears that the panic could spread from financial markets to hit the wider economy.
What is a sub-prime loan and why have they caused all this trouble?
A sub-prime loan is made to someone with a poor or limited credit record.
These loans can be extremely profitable for the lender, who will charge a higher price for the extra risk involved.
In the US, vast numbers of mortgages were sold to low-income families attracted by very low "teaser" rates.
Many of these loans were made based on borrowers' own accounts of their financial affairs, with no proof required.
As interest rates rose and the introductory rates expired, borrowers who had chased the dream of home ownership found themselves unable to afford repayments and started defaulting on the loans.
The sub-prime problem has caused panic beyond the US because, instead of holding loans on their balance sheets, lending banks have been offloading them to investors.
In a global market for debt, financial institutions almost anywhere in the world could have taken on the risk of the loans in return for what seemed an attractive return.
How was this allowed to happen?
Investment banks have come up with ever-more ingenious ways of packaging up debt and selling it on to other financial institutions such as hedge funds, banks and insurers.
This was meant to make the financial system more stable by dispersing risk and reducing the chance of a single bank being sunk by bad debts.
But being able to offload debt encouraged some lenders to loosen their lending standards and make loans to riskier borrowers.
It is not just loans to individuals that have been packaged up in this way.
Corporate loans are also turned into securities and sold on in the market, leaving the lending banks with fat fees for arranging the finance but minimal exposure to the risk.
In particular, banks have fallen over themselves to lend billions of dollars to private equity firms that have used the borrowed money to fund takeovers of companies.
The market panic has caused investors to stay away from these loans, leaving banks with $300bn of unexpected debt.
What are these ingenious products and structures and how do they work?
The basic concept is "securitisation" - parcelling up loans as bonds and selling them into the market, allowing the lender to free capital and transfer risk.
This can be done with assets such as mortgages, credit cards, leases and corporate loans.
But it gets more complicated than that.
To make risky assets like sub-prime loans more attractive, investment bankers have packaged them up with higher quality loans into derivative products called collateralised debt obligations (CDOs) that were given high ratings by agencies.
But as sub-prime defaults increased, investors found themselves sitting on explosive losses from what they thought were low-risk investments.
The panic has also thrown the spotlight on the asset-backed commercial paper market.
Basic commercial paper is an IOU issued by a company or bank to fund its business, typically for three months.
In the asset-backed commercial paper market, (ABCP) banks set up "conduits" - off-balance sheet investment vehicles - which make investments and then issue short-term IOUs to investors to cover their funding needs.
But with the underlying assets sometimes including sub-prime mortgages, the $1.1 trillion ABCP market has dried up with investors refusing to buy paper backed by both risky and low-risk assets.
Wasn't this meant to have dispersed risk throughout the financial system?
That was the idea, but it turns out there is no such thing as a free lunch.
Using impenetrable financial instruments to sell risk in the global market may have spread it around, but no one knows where it is.
Few people paid much attention to IKB until the German bank said earlier this month that it could lose billions of euros from investing through a conduit in sub-prime assets.
With trouble popping up in unlikely places, the market is running scared.
Also, many of the buyers of sub-prime loans and leveraged debt were hedge funds, to which banks had lent huge sums.
With banks suddenly demanding more security from hedge funds and some investors in hedge funds pulling out their investments, some funds have had to sell assets off quickly.
And, having offloaded these debts through the front door, it turns out banks have let them in through the back by using their conduit vehicles to invest in mortgage-backed securities, CDOs and other risky assets.
Why is the crisis of confidence so acute?
The panic has spread beyond sub-prime because people have decided that assets in general were not "priced for risk".
Suddenly, banks and the investors to whom they have been selling all stripes of debt in recent years, have lost faith in what they are buying.
Many of the big banks know that like themselves, their rivals have off balance-sheet conduits that are in some cases chock-full of CDO's and other debt instruments that are so much toxic waste.
What no one knows however is just how bad it is, or how widely spread the damage will be.
So until some clarity emerges, everyone is battening down the hatches.
Private equity firms have shelved takeover plans, banks have stopped lending, and debt investors aren't interested in taking on any more.
Instead widespread de-leveraging is occurring, as investors reduce their debt levels that reached unsustainable levels after years of incredibly low interest rates.
Couldn't someone have spotted this earlier?
Rating agencies such as Moody's and Standard & Poor's, whose job it is to gauge the credit-worthiness of companies as well as financial instruments, granted most CDOs the same rating as US Treasury Bonds, considered the safest of investments.
The European Commission has since opened an investigation into whether they sounded the alarm soon enough, and the US authorities are also expected to examine the issue when Congress returns from recess.
Critics say the ratings agencies are inherently conflicted, raking in huge fees to value the CDOs and other asset-backed securities conjured up by their clients.
The agencies worked closely with the banks to ensure an air of security to a sector that was anything but.
A few lonely voices had raised a flag earlier on including Anthony Bolton, investment supremo at Fidelity, and Warren Buffett, the Oracle of Omaha.
However, bankers and investors were content to march gleefully forward on the belief that the economic cycle had been smoothed, they said, by the opening of new markets abroad and the spreading of risk around the world.
What can central banks do?
Central banks such as the European Central Bank, the US Federal Reserve and the Bank of Japan injected hundreds of billions of dollars in short-term funds as a lender of last resort to desperate banks.
The Bank of England said yesterday that it lent £314m last week at a penalty rate to a bank or banks who had nowhere else to turn.
The US Fed slashed the rate at which it lends to other banks by a half per cent last week, and later said that it was standing by to provide longer-term financing for needy borrowers.
The question, however, is whether the Bank of England, the Fed or the ECB will have to take more drastic action to jolt the financial system back into life.
This could come via a cut in the base interest rate.
In the UK, the BoE Governor Mervyn King has given no indication of a willingness to swerve from the bank's plan to push through at least one more interest rate rise.
How bad could it get?
It is a classic case of the adage: "When America sneezes, we catch a cold." The credit turmoil that began with individual Americans failing to make payments on high-interest loans has already spread to the equity markets in Tokyo, London and the rest of Europe.
Last week, the FTSE had its single largest one-day fall in more than four years.
Investors are fleeing risky assets in droves.
Earlier this week yields on three-month US Treasury bills - a safe haven investment - fell to their lowest levels since 1982.
The financial services industry in the City of London comprised an inordinate proportion of the overall UK economy-about a tenth of the national GDP.
If a slowdown occurs here, the knock-on effects for the rest of the country would be widespread.
Not least would be the housing sector, which has been propped up especially in the Southeast, by City workers armed with bulging bonuses.
In the UK house prices are showing the first signs of slowing after more than a decade of growth.
- INDEPENDENT
