Posted tagged ‘spreads’

Why Stress Test Really Means Guesswork

March 15, 2009

Well, we’ve heard a ton about stress tests recently. Want some details on what a stress test entails? The Journal has some details about the tests here. Now, as much as I think GDP and unemployment are fine things to project forward for economists, let’s walk through the way one would use this to actually price an asset. Let’s start with something simple, like a 10-year treasury note (note that treasury bond specifically refers to bonds with a 30-year maturity). Here are all the components one would need to stress test the value of a treasury note.

  1. Characteristics of the note itself: coupon, payment dates, maturity dates, etc.
  2. What the yield curve would look like at the date you’re pricing the note.

Why would one need to know the shape of the yield curve (term structure of rates)? This is important, in order to “PV” the bond’s cashflows most accurately, one would discount each cashflow by it’s risk–the simplest proxy is to discount each cash flow by the rate of interest one would need to pay to issue a bond maturing on that date. For the government, this rate of interest is the point on the treasury yield curve (actually, the par zero curve) with the same maturity date. An example would be, if I were going to price a cash payment I will receive in two years, and the government can currently issue two-year debt at 5%, I should discount my cash payment (also from the government, since it’s a treasury note) at 5%. Treasuries are the simplest of all instruments to value.

Here’s an example, form the link above, of what a treasury yield curve might look like:

Normal Yield Curve

Now, it is completely and totally guesswork to figure out, given unemployment and GDP figures, what the yield curve will look like at any date in the future. Indeed, one can plug these projections into a model and it can come up with a statistical guess… But the only thing we know for sure about that guess is that it won’t be accurate, although it might be close. However, things like inflation will drive the longer end of the yield curve and monetary policy will drive the shorter end, so these certainly aren’t directly taken from the stress test parameters, but would need to be a guess based on those parameters. This is a large source of uncertainty in pricing even these instruments in the stress test.

Next, let’s examine a corporate bond. What would we need for a corporate bond?

  1. Characteristics of the bond: coupon, payment dates, maturity dates, special features (coupon steps, sinking funds, call schedules, etc.), where in the capital structure this bond sits, etc.
  2. What the yield curve would look like at the date you’re pricing the bond.
  3. The spreads that the corporation’s debt will carry at the date you’re pricing the bond.

Oh no. We already saw the issues with #2, but now we have #3. What will this corporations credit spread (interest/yield required in excess of the risk free rate) at the time of pricing? Will the corporations debt, which could trade at a spread of anywhere from 5 to 1500 basis points, be lower? higher? Will the corporations spread curve be flatter? steeper?

Here is a good illustration of what I’m referring to (from the same source as the figure above):

Credit Spread

There, the spread is the difference between the purple line and the black line. As you can see, it’s different for different maturity corporate bonds (which makes sense, because if a company defaults in year two, it’ll also default on it’s three year debt.. but the companies’ two year debt might never default, but the company might default during it’s third year, creating more risk for three year bonds issued by that company than two year bonds). It shouldn’t be a surprise, after our exercise above, to learn that the best way to compute the price of a corporate bond is to discount each cashflow by it’s risk (in my example above, regardless of whether the company defaults in year two or year three, the interest payments from both the three year and two year debt that are paid in one year have the same risk).

Well, how does one predict the structure of credit spreads in the future? Here’s a hint: models. Interest rates, however, are an input to this model, since the cost of a firm’s borrowing is an important input to figuring out a corporation’s cashflow and, by extension, creditworthiness. So now we have not only a flawed interest rate projection, but we have a projection of corporate risk that, in addition to being flawed itself, takes our other flawed projections as an input! Understanding model error yet? Oh, and yes unemployment and the health of the economy will be inputs to the model that spits out our guess for credit spreads in the future as well.

Next stop on the crazy train, mortgage products! What does one need to project prices for mortgage products?

  1. Characteristics of the bond: coupon, payment dates, maturity dates, structure of the underlying securitization (how does cash get assigned in the event of a default, prepayment, etc.), etc.
  2. What the yield curve would look like at the date you’re pricing the bond.
  3. The spreads that the debt will carry at the date you’re pricing the bond.
  4. What prepayments will have occurred by the date you’re pricing the bond and what prepayments will occur in the future, including when each will occur.
  5. What defaults will have occurred by the date you’re pricing the bond and what defaults will occur in the future, including when each will occur.

Oh crap. We’ve covered #1-3. But, look at #4 and #5 … To price a mortgage bond, one needs to be able to project out, over the life of the bond, prepayments and defaults. Each is driven bydifferent variables and each happens in different timeframes. Guess how each projection is arrived at? Models! What are the inputs to these models? Well, interest rates (ones ability to refinance depends on where rates are at the time) over a long period of time (keep in mind that you need rates over time, having rates at 5% in three years is completely different if rates where 1% or 15% for the three years before). General economic health, including regional (or more local) unemployment rates (if the south has a spike in unemployment, but the rest of the country sees a slight decrease, you’ll likely see defaults increase). And a myrid of other variables can be tossed in for good measure. So now we have two more models, driven by our flawed interest rate projections, flawed credit projections (ones ability to refinance is driven by their mortgage rate, which is some benchmark interest rate [treasuries here] plus some spread, from #3), and the unemployment and GDP projections.

I will, at this point, decline to talk about pricing C.D.O.’s … Just understand, however, that C.D.O.’s are portfolios of corporate and mortgage bonds, so they are a full extra order of magnitude more complex. Is it clear, now, why these stress tests, as they seem to be defined, aren’t all that specific, and potentially not all that useful?

I will destroy this village in order to save it!

February 23, 2008

Can you identify where the title of this post comes from? (Most likely other places, too.)

I was reading this three part series on how a space war with China will affect space assets well beyond the scope of any actual conflict. The relevant quote:

But if the short term military consequences to the United States are not that bad, the long term consequences to all space-faring nations would be devastating.  The destruction … satellites hit during the first hour of the attack considered here could put over 18,900 new pieces of debris over four inches in diameter into the most populated belt of satellites in low Earth orbit. … [Over the course of] the next year or so—well after the terrestrial war with China had been resolved—the debris fields would fan out and eventually strike another satellite. 

These debris fields could easily cause a run-away chain of collisions that renders space unusable — for thousands of years, and for everyone.  Not only is this a quickly growing and important sector of the world’s economy … , but space is also used for humanitarian missions …

Interestingly, it seems like this is exactly what’s going on in the securtization markets right now. Conduits, or investment banks that commit their own capital for making loans which aren’t meant to be held, only securitized, are basically shut down. Why are they shut down? Spreads on Commercial Mortgage Backed Securities have reached astronomical levels relative to where they have been, making it completely uneconomical for re-financing. The longer the conduits stay shut down, the more they downsize. The more they downsize, the less capacity there is. The less capacity there is, the more illiquid the mortgage market becomes for borrowers due to the lack of ability to create new bonds. (This is a very nuanced cause and effect, but many players only buy “new issue” bonds and many indices track newly issued bonds. Once there is a lack of new bonds and those indices become concentrated in older bonds that may have been more aggressively underwritten the sector could become unattractive.) From here, two things happen: borrowers start defaulting because they can’t get new loans, and the aforementioned illiquidity in bonds backed by these loans (in an environment where risk, in the form of defaults, is rising) causes spreads to move even wider (larger spreads = higher rates on commercial mortgages).

Well, this pattern continues, and even the WSJ is talking about how little sense it makes.  (FYI–Caveat emptor for people who consume the WSJ stories on complex derivatives products. There are some issues with how it describes these that I will discuss in a later post.)

At what point would one decide to exit such a market? When does a market seem completely unattractive? Was this disaster necessary to ensure a return to sound credit analysis? Only time will tell.

T-Minus 12 Months to the Rally

February 11, 2008

One trend recently is that many funds or money managers that can raise opportunistic money have started to call asking for distressed opportunities to invest in. These funds are all looking for high return (18-20%) opportunities and usually take a few months to get up and running in addition to a few more months to start sourcing actual buying opportunities. (These funds usually employ leverage, so high return hurdles don’t refer to nominal spreads.) With so many platforms springing up, from both established players and nascent funds, how long can it be before these players fall prey to competition? If you are the same bid for bonds and loans that the larger, relationship firms are, how do you invest your newly raised funds? How long before they relax their return hurdles and the lower parts of the various debt capital structures finds buyers at tighter levels? I guess we’ll see…


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