I’ll share the practical workings of interest rate swaps, cross currency swaps, cross currency basis and related variations. The content would build on the foundations discussed in the section on Time Value of Money and cash products.
\[ \text{PV of fixed rate cash flows}= C \times DF_1 + C \times DF_2 + ... + C \times DF_n \]
\[ \text{PV of floating rate cash flows} = FLR_1 \times DF_1 + FLR_2 \times DF_2 + ... + FLR_n \times DF_n \]
Where C is the par fixed swap trading in the market,
DFn is the discount factor for the nth time period
FLRn is the expected or projected floating rate for the nth time period
Mathematically then the observed par fixed swap rate C can also be derived by equating the two notations above and plugging in the expected floating rates in progressive time periods.
Importantly,
\[ DF_n = \dfrac{1}{ {( 1 + FLR_n )}^n } \]
Assuming for the sake of simplicity the cash flows are funded at the floating rate. We discuss a more nuanced concept of the discount curve being different from the projected floating rate curve later in the section.
\[ DV01 = - \text{Modified duration} \times M \text{arket value of the Bond notional} \times 0.01\% \]
The same for a swap would be denoted as
\[ DV01 = - \text{Mod duration of the fixed leg} \times ( 1 + PV_{\text{fixed leg}} ) \]
\[ - \{- \text{Mod duration of latest reset} \times ( 1 + PV_{\text{reset}} )\} \]
Table 1 – Bucketing and Leverage of spot and forward starting swaps
| Tenor bucket | Spot 6y | Spot 8y | 1y forward 1y | 4y forward 1y | 3y forward 2y |
|---|---|---|---|---|---|
| 1y | +10K | ||||
| 2y | -20K | ||||
| 3y | +15K | ||||
| 4y | +40K | ||||
| 5y | -5k | -50K | -25K | ||
| 7y | -5k | -6.6k | |||
| 10y | -3.3k | ||||
| Leverage | 2x | 5x | 2.5x |
* Standard DV01 risk assumed to be $10K, swap direction is received fixed rate
Source: Pandemonium.
Leverage multiple on Rxy swap w.r.t (x+y) year tenor =
\[ \dfrac{ ( x+ y)}{y} \]
Swap unwinds are computed as the present value of the cash flows (positive or negative) reflected in the difference between the traded fixed rate and the current market fixed rate. As the swap ages and market movement changes the projected floating rate (the current par rate) it results in a non-zero present value relative to the original fixed rate. In addition to the fixed rate differential, the unwind value also needs to be adjusted for any short stub valuation i.e. the residual current floating rate period that uses the updated interpolated floating rate vs the original floating rate to calculate the stub unwind value.
As an example of an aged interest rate swap – Consider a received 5y swap at a fixed rate of 5% against a 3m floating index. The swap has aged by a month since the start date of the swap and the first floating rate was fixed at 4%. I’ll discuss two different methods for the unwind:
Other considerations while entering into a swap are counterparty credit risk and funding of cash flows (variation margin, CSA, CVA, FVA, wrong way risks to be discussed in detail in the risk section later).
Importantly on any swap, the 0 PV at the time of entering it is the result of PV of the expected average cash flows of the floating leg being offset by the PV of the expected average cash flows of the fixed leg, “average” being the key word. In other words for both a steep and or inverted yield curve there will be cash flow mismatches between floating and fixed legs on select reset periods (can very well be at the start of the swap too) even though the sum of the PV of all mismatches would be 0. These mismatches create counterparty credit risks (assuming no CSA/credit mitigation documents) and the risks change with movements in the underlying market.
Now comes the funding of these mismatches. The rate of interest at which a counterparty funds these cash flows is the discount rate (which determines the discount curve) to calculate the PV of these cash flows. The traded swap curve however is the projection curve i.e. projects the expected floating benchmark across tenors. THE TWO CAN BE DIFFERENT. In case the CSA is in place the discount rate is the rate the two parties pay each other on the variation margin (CSA discounting), while in the absence of a CSA, discount rate is the rate at which the dealers fund their variation margin. For the latter, banks reflect them as FVA (funding value add) to be charged to the client that differs for different dealers depending on their respective funding curves.
As an example when you trade a USD LIBOR swap, the cash flows are projected using LIBOR, but they are discounted using the rate at which the two parties fund the cash flows i.e. USD OIS in most cases for inter-bank CSA participants. Hence while computing the PV of cash-flows, one would notice a LIBOR-OIS basis risk that would need to be hedged. Similarly for a local currency EM swap, say KRW NDIRS – the projection curve would project the 3m CD index while the cash flows would be discounted on USD OIS (assuming benchmark funding rate for dollar-based counterparties). Given that KRW PV would need to be funded against USD OIS the actual discount curve would be the KRW ND CCS vs USD OIS. As of today since ND CCS trades against USD SOFR, while computing the PV we would technically have some SOFR-OIS basis risk even though negligible as market uses these rates interchangeably.
Trivia.Difference between 3m and 6m USD LIBOR came into prominence during the Global Financial Crisis when the 6m LIBOR curves started baking in a larger credit risk premium vs the 3 month benchmark. Previously cash flows on both 3m and 6m LIBOR swaps were discounted off their respective projection curves (as 6m could be interpolated exactly from the 3m curve) but once the curves started diverging dealers had to rebuild their models to discount them both off the USD funding curve.
This was 3m libor flat for most banks in the pre-CSA world and later changed to OIS once credit mitigation documentation was put in place.
As part of CSA negotiations dealers also discussed the provision for margin posting in different currencies. For e.g. it was quite common in Japan to have CSAs that allowed either USD or JPY cash margins to be posted. More interesting is the fact that the funding rates on different currencies naturally follow their respective money markets and don’t really account for FX equivalent rates (cross currency basis discussed later). This gives rise to an optionality within the CSA whereby dealers can choose to switch between the currencies for margin posting (and effectively the discount curve for their trades) based on which one is cheaper to fund. This optionality is difficult to price due to the non-existence of observable trading prices for the correlation/ volatility between the two discount curves. But if dealers discover a way to hedge it, it could have an impact on pricing of swaps documented on dual currency CSAs.
Since we haven’t yet discussed the details of a collateral swap agreement and related risk mitigation yet (to be covered later) for the sake of completion I’d just like to mention the concept of a cleared swap. A cleared swap places an exchange/clearing house in between the payer and the receiver to eliminate counterparty credit risk, by taking the onus of margining (initial and variation margins) from both parties. It also helps facilitate block unwinds at portfolio level for swaps traded with different counterparties but facing the same clearing house.
Exchange basis (LCH-CME, LCH-JSCC etc.) – When net open positions or one sided positions of dealers become large on an exchange, the requirements to fund the Initial Margin increases making it more costly for dealers to trade more of the same direction on those swaps. In other words dealers are willing to pay a higher cost to get the other side of the swap facing that exchange/clearing house compared to what they are willing to pay for the same on other exchanges. This is what leads to a basis to develop for the same swap between two different exchanges. For example, asset managers that mostly dealt on CME and were fixed rate payers (assuming hedges on long bond positions) created sizable received open positions with dealers. These dealers were willing to pay higher for the same swap on CME compared to LCH (basis visible around mid-2015) as the higher cost was being offset by lower margin requirements for positions compressed on CME.
Table 2 – Comparison between IRS (Single Currency Swap) and CCS
| IRS | CCS | |
|---|---|---|
| Notional Exchange | No | Mostly yes, though coupon only swaps don’t have any notional exchange |
| FX risk | No | Yes as stated above |
| Type of swap | Fixed/Float typically, float/float on 2 different indices of the same currency | Fixed/Float, Fixed/Fixed (typically used for corporate liability swaps), Float/Float |
| Discount Curve | Function of CSA | Function of CSA |
| Credit and Funding charges | CVA and FVA as discussed earlier | CVA and FVA charges are larger owing to FX vol risk on foreign currency notional in addition to rates vol |
| Duration/Rates risk | Same as the duration of the fixed rate leg | That of fixed rate leg in case of fixed/floating and could be on both legs in case of fixed/fixed |
| Unwind Value | Function of change in interest rates for onshore swaps. For USD based investors trading local currency swaps there is spot FX risk on unwind PV. | Function of change in interest rates and Spot FX rate. |
Source: Pandemonium.
Cross Currency Basis Swap – is simply a float/float cross currency swap and primarily a financing instrument traded in the inter-bank market as a foreign currency floating rate against the hard/benchmark currency floating rate +/- spread. Basis swap levels therefore are an indicator of the magnitude of funding cost of the local currency in terms of the foreign currency.
In terms of cash flows they can be understood as a series of FX swaps, reset at prevailing market rates.
Indicative terms of a basis swap contract for client ABC: assuming client pays 5y USDJPY cross currency basis swap (JPY TONA/OIS vs USD SOFR)
Trade Date: Today
Swap Start Date: T+2/Spot Date/Forward Start IMM date
Maturity Date: end date as per the tenor of the basis swap (eg. 5y)
Notional Amount: Generally in base currency (eg. USD 100 mio)
Foreign Currency Notional: USD 100 mio x USDJPY FX rate effective on the start date
Notional Exchange: at start date and maturity
JPY Floating Rate: JPY TONA/OIS
USD Floating Rate: SOFR – xxx spread
JPY Floating Rate Payer: ABC i.e. borrows JPY and lend USD
USD Floating Rate Payer: Dealer i.e. lends JPY and borrows USD
JPY Floating Rate index Convention:
USD Floating Rate Convention: 3m USD SOFR compounded
Holiday Convention: Tokyo, New York
Trivia. While basis swaps have been dealing for a long time in deliverable and developed market currencies – they have unfortunately not gained as much popularity with developing Asian markets. That’s primarily because the Asian local currency floating benchmarks were non-existent prior to the Asian Financial Crisis. There were literally no domestic interest rate policies or domestic swap (IRS) markets. Whereas there were vibrant long dated FX markets which facilitated the development of Fixed (local currency)/ Float (USD) longer dated cross currency swaps much earlier. To this day one doesn’t readily find liquidity in basis swaps in these Emerging market currencies and basis quotes are backed out of fixed float CCS and IRS / NDIRS separately.
Now as a follow-up here’s the intuition behind the cross currency basis product – the term basis refers to the difference between the yield differential that should get reflected in FX swaps as per covered interest parity vs what actually gets reflected owing to the relative demand for the foreign currency vs the base currency or vice versa.
To understand this numerically, it’s best to consider cash flows – let’s take the eg. of one of the more actively traded markets – SGD FX points and the corresponding SGD OIS vs USD SOFR.
Paying 6m USDSGD points or a sell buy on the 6m FX swap would entail:
Near leg (spot in this case): Lend USD and borrow SGD
At maturity do the reverse: return the SGD and receive back USD
Recall that an FX swap is a fixed base currency notional exchange versus the foreign currency at a zero coupon and the FX points for the tenor of the swap determines the foreign currency notional at maturity which in theory implies the FX rate after 6m as per covered interest parity. But let’s see what happens in reality:
Current Spot: 1.37
Base currency fixed notional: USD 100 mio
SGD notional at spot = SGD 137 mio
Market mid on 6m USDSGD FX points: -50pips
6m FX outright: 1.37 – 0.0050 = 1.3650
If we were to do the same trade assuming market interest rates:
\( \text{USD Cash Flow} = \)
\[ 100 mio (1+ \dfrac{ 4.70\%}{ 2} ) \]
\[ = USD 102.35 \]
\( \text{SGD Cash Flow} = \)
\[ 137 mio (1+ \dfrac{ 4.00\%}{2} ) \]
\[ = SGD 139.74 \]
\( \text{Implied USD SGD outright in} 6m = \)
\[ (\dfrac{ 139.74}{ 102.35} ) \]
\[ = 1.3653 \]
\( \text{Implied} 6m \text{points as per covered interest parity} = \)
\[ 1.3653 - 1.3700 = -47 \]
In conclusion: market traded 6m USDSGD outright shows a larger SGD FX appreciation than what’s implied by interest rate parity. Thus the implied SGD yield against USD SOFR should be lower than the local market SGD OIS rate. The difference between the two rates is known as the cross currency basis for SGD against USD SOFR.
Mathematically then for a specific tenor,
Fixed Rate CCS – Fixed Rate IRS = Basis for that tenor
Connecting the Dots. We have discussed both FX swaps and cross-currency swaps and now understand that both products are a reflection of the interest rate differential between the two currencies, with just different cash-flow schedules. I’ll share an illustration below that takes market-traded USDINR FX points, to first calculate the implied zero INR rate (or what’s popularly known as the FX implied INR yield) and use those zero rates to calculate the par CCS yields via bootstrapping.
INR FX implied yield – is effectively the zero rate implied by USDINR FX points and the USD zero rate. In the Quantitative easing era zero rates for several years were literally close to zero, such that FX implied yield was almost interchangeably used with the cost of generating local currency funding; dollar liquidity glut made USD funding available at almost 0 spread over risk free rate. But as USD rates went up and steep spreads on USD risk free rates were baked into funding costs the investment carry dynamics completely changed (more on this in the financing section).
\[ \{ 1 \times {( 1 + 1.35\%)}^{0.25} \} \times 77.24 = 76.515 \times {( 1 + y\%)}^{0.25} \]
,where y is the annualised implied INR zero rate.
\[ = \{ 1 \times {( 1 + 1.35\%)}^{0.25} \} \times 72.50 = 77.50 \]
\[ [\dfrac{ 77.50}{ 76.515} ]{}^{(\dfrac{1}{ 0.25} )} - 1 = 5.25\% \]
Table 3 – Conversion of FX points to FX implied Zero Rates
| Tenor | Time in years | USDINR FX points | O/R forward price | $ zero rate | Future value of 1$ | INR future value | Implied INR Zero rate |
|---|---|---|---|---|---|---|---|
| 3m | 0.3 | 72.5 | 77.2 | 1.4% | 1.0 | 77.5 | 5.3% |
| 6m | 0.5 | 143.5 | 78.0 | 2.0% | 1.0 | 78.7 | 5.8% |
| 9 m | 0.8 | 218.0 | 78.7 | 2.3% | 1.0 | 80.1 | 6.2% |
| 1 y | 1.0 | 298.5 | 79.5 | 2.6% | 1.0 | 81.6 | 6.6% |
| 18 m | 1.5 | 459.5 | 81.1 | 2.9% | 1.0 | 84.7 | 7.0% |
| 2 y | 2.0 | 619.6 | 82.7 | 3.1% | 1.1 | 87.8 | 7.6% |
| 3 y | 3.0 | 932.6 | 85.8 | 3.1% | 1.1 | 94.1 | 7.2% |
Source: Pandemonium.
Table 4 – Bootstrapping Zero rates to Par rates
| Tenor | Time in years | Implied INR Zero rate | Discount Factors | Par semi CCS Yield |
|---|---|---|---|---|
| 3m | 0.3 | 5.3% | 1.0 | 5.2% |
| 6m | 0.5 | 5.8% | 1.0 | 5.8% |
| 9 m | 0.8 | 6.2% | 1.0 | 6.1% |
| 1 y | 1.0 | 6.6% | 0.9 | 6.5% |
| 18 m | 1.5 | 7.0% | 0.9 | 6.9% |
| 2 y | 2.0 | 7.2% | 0.9 | 7.0% |
*Zero rates and CCS yields have been rounded up to the second decimal
Source: Pandemonium.
\[ \dfrac{1}{ {( 1 + R_{z,t} )}^t } \]
,where Rz,t is the zero rate for tenor t.
So,
\[ 3m \text{discount factor} = \dfrac{1}{ {( 1 + 5.25\%)}^{0.25} } = 0.9873 \]
\[ 1 = \dfrac{ ( 1 + \dfrac{C}{2} )}{ {( 1 + R_{z,6m} )}^{0.5} } \]
which clearly shows:
\[ C_t \ne R_{z,t}, \]
\[ 1 = ( \dfrac{ C }{ 4 } ) \times 0.9873 + ( \dfrac{ C }{2} ) \times 0.9557 + 1 \times 0.9557 = 6.11\% \]
Connecting the Dots. Let’s crack down on some frequently used interest rates lingo to define the frequency of their payments/compounding so all terms used in this section are absolutely clear:
Given that this is an exchange of notional in two different currencies on floating rates there is negligible rates duration in a basis swap. Risk on it largely comes from the FX movement in course of the tenor of the swap and only pending final exchange of notional.
Trivia. Pre-CSA basis swaps in Japan would reset the notional on every coupon date. Basis swaps – since floating – are less sensitive to movements in rates due to short duration tenors of the floating legs. However mark-to-market is sensitive to FX rates as the trade’s notional exposure to the FX rate. This also implies a higher counterparty credit exposure. The JPY-USD basis market tackled this issue by resetting the foreign (JPY) notional on each coupon reset date. For example if a basis swap was entered for 5 years at a spot rate of 100 JPY per USD and the FX rate at the end of the 1st floating rate period moved to 120, the difference of 20 JPY would be additionally lent by the JPY lender to the JPY borrower thus changing the JPY notional lent/ borrowed on the swap for the next period. Notice then, that not only are the respective currency coupons floating, the foreign/local currency notional are also floating. This matching of JPY lent or borrowed was to be done every interest reset period to exchange the mark-to-market on FX movements, which is exactly what happens under a CSA (albeit daily) thus reducing the credit exposure on these swaps. These were known as basis swaps with resetting notional.
Table 5 – Comparison between Long Term FX Swap and CCS
| Long Term FX Swap | CCS | |
|---|---|---|
| Duration | Equivalent to the duration of a zero coupon bond | Equivalent to the duration of a fixed coupon bond |
| Cash flows | No interim cash flows, only initial and final cash flows | Cash flows of fixed vs floating rate bonds based on payment frequency |
| Credit and Funding Charges | Charges are higher as no interim cash flow exchange increases counterparty exposure | CVA and FVA charges subject to FX risk on foreign currency notional |
| FX risk | Equal to FX notional on the foreign currency leg | Equal to FX notional on the foreign currency leg |
| Rates Risk | On both fixed notional (interest rate) legs as swap PV changes with interest rate differential | Equivalent to the fixed leg of the swap since floating leg has minimal duration |
For the sake of completion of all payment frequency types of CCS consider an exchange of different currency notionals at fixed coupons. Salient Features below:
I do hope I’ve been able to keep you engaged and intrigued so far by following a building blocks approach to learning. Extending it further let’s combine ALL that we have discussed so far to build a bigger block of Cash and Financing products.
Look forward to meeting you there.
Pandemonium is markets intelligence with the intuition of a dealing room — fifty-three lessons across rates, credit, FX and options. The intuition first, then the mathematics, then the trade. Written by Varda Pandey.
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