Thursday, October 9, 2008
One, particular confluence of credit and FX markets is the freeze up in the lending markets. In a fine essay by Thomas Stolper and others - they hint at the mechanics and the consequences of this relationship. Most banks have short dated FX obligations and longer dated domestic currency obligations. As the overseas short term lending markets freeze -- we get banks scrambling to find assets to pay out their obligations. Since most central bank lending mechanisms only lend in their domestic currencies -- most banks are forced to borrow domestically, convert that into the foreign currency and payout. The dollar denominated debts are the highest in the world, followed by Euro denominated and so on. So, as the US lending market freezes - one should the rising demand in the USD (as counterintuitive as it might seem).
However, this is one piece of the puzzle. The trader is only concerned with the net flow of dollars and changes in value - however, it is important to keep in mind the market imperfection (frozen credit markets) work its way through structural constrains.
Sunday, February 24, 2008
i.e., Modern money is backed by only goodwill of the issuing government and the value that we, the holders, deem it to have. In the past, money was backed by commodities. Cowries, gold, oil, wood , slave girls etc., The Great British Empire was run on backed gold -- of varying quality -- backed by an asset, nevertheless. Since 1945-- the USD which has been the de facto currency of the world. On the extreme de jure currencies might exist but nevertheless be virtually ignored -- as in say, Afghanistan under the Taliban. Alongside, the key historical aspect is there has often only been a single de facto currency, on average, since the Enlightenment. Even the Nazi Germans during the forward stashed away their currencies in GBP.
What is peculiar about past four years is the following. We have two major currencies backed by nothing. And it seems increasingly clear there are two competing de facto currencies. The USD and the Euro. While the two currencies have had differing changes in value relative to other currencies over the past year (and more). See two cool graphs here: Euro & USD. The US is a behemoth with a cashflow problem; the Euro is essentially confederate money in a continent with a demographic problem. (See an interesting paper on confederate money.)
Now, the critical problem is globally: what is the optimal holding between USD and EUR. No ones the answer. In fact, one doesn't know if this is dichotomous choice itself is a false one. Increasingly, there are two other alternatives. Holding Gold itself. And as well, the basket of non-USD and non-EUR currencies. These are tough questions - but one thing is clear. The times have changed -- and we are, perhaps, entering for the first time since 1700s into an era of financial history that isn't very well known or even how to frame the questions correctly.
My own understanding of all this, on a weekend of Oscars, is more or less summarized by the preface to this song...
Thursday, February 21, 2008
At the heart of the present crises that we are three factors: (i) default fears (ii) draining of liquidity (iii) industrial downturn. What has most gotten attention in popular press is default fears -- with default in household mortgages that has captured popular imagination. It is important to thus get briefly acquainted on how mortgage defaults (MD) are understood in most pricing or analytics.
MD is defined, in general, as when both of the following events occur: (i) unable to pay 3 consecutive monthly payments (ii) the equity in the home diminishes to leave no prospects of refinancing. Further, MD rates have a following shape. At first they rise, and then really spike up and then they decline -- graphed over years of mortgage existence.
Typical mortgages made out in the subprime market have been adjustable rate mortgages (ARMs) -- where the coupon is fixed for a while and then begins to reset periodically. Even the 30 year ARM in the regular markets are "5 x 1" (fixed for 5 years, and resets annually). In contrast, the 30 year ARM in a subprime markets are "2 x 28" (fixed for 2 years, resets semiannually for the next 28 years). Typically this reset is based of some pre-agreed index that tracks the cost of money, conditional on borrower quality, across the economy. So, if the generic interest rates begin to rise in the economy -- associated payable rates by the mortgage borrower are reset at a higher rate. What makes things worse is that most of these ARMs have an early "interest only" feature. Resultantly, as the "interest only" period finishes off -- the mortgage borrower has to start paying off for the principal component as well.
One of the critical issues every mortgage lender worries about is the prepayment of the lent amount. Typically, most of the pricing is done with some sort of prepayment model. The prepayment is a function of (i) available refinancing (ii) housing turnover (iii) curtailments (paying more every month than obligated) (iv) defaults. Typical modeling efforts of prepayment are applicable to a tranche of loans. As opposed to modeling prepayment for each loan.
Another layer of complication is to wonder about how to model the extent of loss that occurs as a mortgage defaults.
Now imagine writing securitized tranches that are sold which contain slices of mortgage backed securities -- i.e., CDOs on MBSs. It is not surprising then that we end up having this situation.
In essence, things get hairy pretty fast...
Friday, November 30, 2007
- Long Ringitts, SGD and Taiwanese dollars – all funded by USD.
- Sell pound-sterling against yen.
- Sell gold.
- Borrow in CAD, GBP, USD and buy BRL, RUB, CZK.
- Sell 10-year CAD bond futures and receive fixed on 10-year CHF swaps.
Tuesday, November 20, 2007
- Changes in Terms of Trade (= price of exports divided by price of imports) is a function of changing commodity prices (energy, industrial metals, agriculture, live stock).
- Extract sensitivity estimates (the coefficients in a regression) to predict terms of trade.
- Changes in Real Exchange Rates ( = price of one unit foreign currency in domestic currency * ratio of foreign and domestic price levels) is a function of two key parameters.
- Terms of Trade
- Relative productivity levels -- measured by, say, per-capita output per hour etc.,
My own guess is that there are three key parameters that affect the short term exchange rate fluctuations:
- Global capital flows -- that chase the second-order effects anticipated changes in terms of trade.
- Changes in US deficits (budgetary and trade) -- this is particularly accentuated by the coming US electoral-cycle.
- Idiosyncratic events -- particularly emerging market macroeconomic instabilities.
Friday, November 16, 2007
Standard Black Scholes pricing assumes a constant vol. The underlying implication being that the logarithm of the returns is normally distributed – and thus contained in it, a constant standard deviation (the constant volatility). In the market, there are other factors are play – such as supply/demand, risk-premia etc., -- all that contribute to, what Keynes memorably called “animal spirits” in the option pricing market. Typically, if the market expects a greater likelihood of the underlying exchange rate to go past the strike, the calls on the currency tends to get priced more expensively than the puts.
An option on call USD–CAD put refers to the call on the USD and the put on the CAD. So, the holder of the option has the right to buy the USD (convert the CAD notional at a prespecified rate). Equivalently, the holder of the option has the right to sell the CAD at a prespecified rate.
A spot price of 0.97, i.e., one USD can be exchanged for 0.97 CAD; with a strike of 1.01 on a call USD-CAD put refers to the right to buy one USD in exchange for 1.01 CAD. Tersely, the spot is 0.97 and the strike is 1.01 with a CAD-put. On the expiry date if the spot prices are 1.00, then the buyer of the call (with say 101 CAD in his account) would not exercise his option to buy a USD at 1.01 CAD when he can easily buy the same USD at 1.00 CAD. In this example, the USD is anticipated to appreciate. So, the call option on the USD-CAD is evidently ‘worth more” than a corresponding put option. i.e., if an appreciation is anticipated the corresponding call is priced at a higher level. This supply-demand forces are not a part of the Black Scholes derivation. Since, most parameters are fixed – the only “tweak-able” parameter is the vol – or the implied vol.
A 25-delta call refers to a call option where the strike above the spot (thus an out of the money option). So, in the above – it is clear that a 25-delta call has different implied vol than a 25-delta put. The “25” in the above refers to the fact if the underlying exchange rate increases by 1, the corresponding the call option value rises by 0.25. So, to arrive at a delta-hedge a corresponding position has to be taken in the underlying. The market convention of 25-delta is agreed upon – as one that is sufficient to capture the expectations regarding changing underlying prices. Of course, you can have 10-delta, 50-delta and so on.
A risk reversal is thus, the difference in implied vols between, ceteris paribus, out of the money calls and out of the money puts. Quoted thus, a rise in the risk-reversals means that as the currency appreciates, the volatilities are likely to rise. Instead, if risk-reversal are quoted as put – call. Then a rise in risk-reversal refers to the fact that as currency depreciates the vols are likely to rise.
A useful example of the trade flow is as follows: (courtesy gfmi.com)
Assume an appreciation of the USD against the CAD over the next 3 month period (mean-reversion??). 3-month 25 delta USD-CAD risk reversal of 0.15 -.28% at a vol of 8.5% means:
1. Buy the 25 delta USD call/CAD put at 8.65% and sell the USD put/CAD call at 8.5%. The trader shells out 0.15%. i.e., he is paying a skew-premium of 0.15% in anticipation of a USD rise.
2. Sell the 25 delta USD call/CAD put at 8.78% and buy the USD call/CAD put at 8.5%. The trader earns the .28% spread.
On option desks, rules of thumb Rule! So, to extract the implied skewness, it is pretty standard to (a) calculate the risk-reversal (b) calculate risk-reversal per-unit of ATM vol. Risk reversals.
The big challenge is what to do when appreciations have different vols than depreciations. If you know how to deal with that – then there is some money to be made and a heck-of-career to be had!