Types of Interest Rates
- Interest rates increase as the credit risk of the underlying instrument increases.
- Credit risk: This is the chance that a borrower won't be able to repay a loan. The higher the risk, the more likely it is that the borrower will default.
- Interest rate: This is the price you pay to borrow money. It's essentially the fee the lender charges for taking on the risk of lending you money.
- So, when the credit risk of a loan or investment increases (becomes riskier for the lender), lenders typically respond by raising the interest rate.
- This makes the loan more expensive for the borrower, but it also compensates the lender for the greater chance of not getting their money back.
- Here's an analogy: imagine lending money to a friend. If it's your best friend with a steady job, you might be happy to lend them money at a low interest rate. But if it's someone you barely know with a history of financial trouble, you'd probably charge them a higher interest rate to account for the greater risk.
- It's important to note that interest rates are also influenced by other factors, like overall economic conditions and monetary policy set by central banks. But credit risk is definitely a major player.
- Treasury Rate
- Bench mark rate or Treasury rate is generally considered to be risk free rate at government of country borrow in its own currency.
- LIBOR
- London Interbank Offer Rate - LIBOR
- It is based upon the estimations of the certain financial instituitions though larger but handful, which subjected it to potential manipulation.
- They could be biased as they determine the borrowing and lending rates.
- And this is the reason of why LIBOR is being phased out in the Mid of 2023.
- SOFR
- The Secured Overnight Financing Rate (SOFR) is a one-day, repo-based rate that is derived from actual transactions.
- It is one of the proposed replacements for LIBOR.
- Repo
- The “repo” or repurchase agreement rate is the implied rate on a repurchase agreement.
- In a repo agreement, one party agrees to sell a security to another with the understanding that the selling party will buy it back later at a speciied higher price.
- The interest rate implied by the price differential is the repo rate.
- Suppose there are two banks, Borrower A and Lender B
- Borrower A gives its securities of value $90 to Lender B inorder to get loan of $90.
- Borrower A promises to Lender B to repurchase securities in future @$100.
- To arrive interest rate using repo rate
- Borrower A took loan of $90 gave the securities worth of $90
- Now Borrower A pay $100 and get back the securities
- Rate of Interest or Rate of Return = 100 / 90
- The most common repo is the overnight repurchase agreement.
- Overnight Rate
- The overnight rate is the rate at which large financial institutions borrow from each other in the overnight market, without security.
- In US it is called as Federal Fund Rate and is monitored and influenced by the central bank.
- If a financial institution borrows (lends) funds at the overnight rate, the rate it pays (earns) during the period is the weighted average of the overnight rates.
The Bloomberg Short-Term Bank Yield Index (BSBY) and overnight-based reference rates are both used to gauge short-term borrowing costs, but they operate differently and serve distinct purposes. Here’s a comparison of the two:
Bloomberg Short-Term Bank Yield Index (BSBY)
Nature: BSBY is a forward-looking term rate that reflects the average expected bank borrowing cost over a specified term. It's designed to provide a benchmark for short-term borrowing and lending rates.
Calculation: BSBY is based on a panel of contributing banks' unsecured borrowing costs, which are estimated for various maturities (e.g., 1 month, 3 months). It incorporates market expectations and is intended to reflect current borrowing conditions.
Use Case: BSBY is useful for financial products that need a forward-looking reference rate. It’s commonly used in derivative contracts, loans, and other financial instruments that are priced off term rates.
Transparency: As a term rate, BSBY provides a clear picture of expected borrowing costs over future periods, offering more visibility into the cost of credit over time.
Overnight-Based Reference Rates
Nature: Overnight-based reference rates, such as the Secured Overnight Financing Rate (SOFR) or the Euro Short-Term Rate (€STR), are backward-looking and reflect the average rate at which banks borrow overnight, usually secured by collateral.
Calculation: These rates are based on actual transactions or survey data for overnight borrowing and are updated daily. They capture the cost of short-term borrowing on a very granular, day-to-day basis.
Use Case: Overnight rates are commonly used for products that require a daily, real-time reference. They are especially relevant for markets and products where precision and current data are critical.
Transparency: They offer a very precise view of the cost of borrowing on an overnight basis, making them useful for products where short-term, accurate rates are necessary.
Key Differences
- Term vs. Overnight: BSBY provides rates for various terms (e.g., 1 month, 3 months), while overnight rates are specific to borrowing costs over a single day.
- Forward-Looking vs. Backward-Looking: BSBY is forward-looking, reflecting expectations for future borrowing costs, whereas overnight rates reflect actual borrowing costs from the previous day.
- Application: BSBY is used for financial instruments that need a term structure of rates, while overnight rates are more suitable for products requiring precise daily rates.
In summary, BSBY and overnight-based reference rates serve different needs in the financial markets, with BSBY providing term structure and forward-looking insights, and overnight rates offering precision and current data.
- Longer-term agreements are called term repos.
- Depending on the parties and structure involved, there is some credit risk with repurchase agreements.
- OIS
- Overnight Index Swap, is an interest rate swap is an exchange contract generally fixed vs floating.
- Fixed vs. Floating Rate Swap:
- In an OIS, one party agrees to pay a fixed interest rate (the OIS rate) for a certain period.
- The other party agrees to pay a floating rate based on the geometric average of overnight interest rates (typically federal funds rate) over the same period.
- Geometric Average:
- The floating rate is calculated as the geometric average, not the arithmetic average, of the daily overnight rates.
- This means it considers the compounding effect of interest rates over the period.
- Payment Determination:
- The party that agreed to the fixed rate makes a payment if the OIS rate is higher than the geometric average.
- Conversely, the floating rate party pays if the geometric average is higher.
- This essentially determines who benefits from changes in short-term interest rates during the OIS term.
- Risk Management:
- OIS are commonly used for managing interest rate risk.
- By locking in a fixed rate, one party can protect themselves from rising interest rates, while the other party can benefit if rates go down.
- Market Benchmark:
- OIS rates are often seen as a benchmark for short-term interest rate expectations.
- The spread between OIS rates and other rates, like LIBOR, can indicate market sentiment about future interest rate movements.
- Participants:
- OIS are primarily traded between banks and other financial institutions.
- However, they can also be used by asset managers and hedge funds for interest rate speculation.
- Treasury rates, such as those for T-bills (short-term) and T-bonds (long-term), are frequently regarded as benchmarks for nominal risk-free rates in financial markets. These rates are considered risk-free because they are backed by the full faith and credit of the government issuing them (in this case, the US government). However, there are nuances in how these rates are perceived by different market participants.
- Derivative traders, in particular, often find Treasury rates to be lower than what they consider truly risk-free. This perception arises because demand for Treasuries is not solely driven by market forces but also by regulatory requirements. For instance, banks and financial institutions often hold Treasuries as part of their regulatory capital requirements or liquidity buffers. This regulatory demand creates artificial buying pressure for Treasuries, driving their prices up and their yields (or rates) down.
- Example Scenario:
- Let's consider the current market conditions where:
- T-bill Rate: 0.1% (annualized rate for a 3-month T-bill)
- OIS Rate: 0.5% (overnight indexed swap rate for the same period)
- In this scenario:
- T-bill Rate (0.1%):
- This rate is considered the risk-free rate for short-term borrowing or lending in theory, as it reflects the yield on a short-term US Treasury security.
- However, derivative traders might argue that this rate is artificially low due to the regulatory demand for Treasuries.
- They believe this rate does not adequately reflect the true opportunity cost of capital in the market because it is influenced by factors other than purely market supply and demand dynamics.
- OIS Rate (0.5%):
- The overnight indexed swap rate represents the market's expectation for the overnight rate over a specified period (like 3 months).
- Unlike Treasury rates, OIS rates are influenced primarily by market forces and are less affected by regulatory demand for Treasuries.
- Derivative traders often prefer to use OIS rates as a proxy for the risk-free rate in short-term derivative pricing because they believe OIS rates better reflect the true cost of capital in the market without distortions caused by regulatory requirements.
- Why OIS Rates?
- Reflecting Opportunity Cost:
- OIS rates are seen as reflecting a trader's true opportunity cost of capital because they are based on actual market transactions rather than regulatory-driven demand.
- Market Dynamics:
- Traders use OIS rates to price derivatives because they believe these rates are more indicative of the market's consensus on short-term risk-free rates, accounting for supply and demand dynamics in the interbank lending market.
- In summary, while Treasury rates are considered nominal risk-free rates due to government backing, derivative traders often prefer to use OIS rates as a more accurate reflection of the true risk-free rate for short-term transactions. This preference stems from the belief that OIS rates better capture the opportunity cost of capital in the market, considering market dynamics rather than regulatory influences on Treasury prices.
Compounding Frequencies
- If we have an initial investment of A that earns an annual rate R, compounded m times a year for n years, then it has a future value of:
- FV1 = A ( 1 + R / m ) ^ m*n
- If our same investment is continuously compounded over that period, it has a future value of:
- FV2 = Ae ^ R*n
- For any rate, R, FV2 will always be greater than FV1. The difference will decrease as m increases. In fact, as m becomes ininitely large, the difference goes to zero.
- In most circumstances, rates are discretely compounded, so we need to use the continuously compounded rate that gives the same future value. Using the previous two equations, the goal is to solve the following:
- A ( 1 + R / m ) ^ m*n = Ae ^ Rc*n
- R = discreate compounded rate
- Rc = continuously compounded rate
- We can solve for Rc as:
- Rc = ln((1 + R/m)^m)
- We can solve for R as:
- R = m ((e^Rc/m) -1)
- EXAMPLE: Computing continuous rates
- Suppose we have a 5% rate that is compounded semiannually. Compute the corresponding continuous rate. Repeat this for quarterly, monthly, weekly, and daily compounding.
- Semi annually
- Rc = 2ln ( 1 + 0.05/2 ) = 0.049385
- Quarterly
- m = 4
- Rc = 4ln ( 1 + 0.05/4 ) = 0.049690
- Monthly
- m = 12
- R = 12ln ( 1 + 0.05/12 ) = 0.049896
- Weekly
- m = 52
- R = 52ln ( 1 + 0.05/52 ) = 0.049976
- Daily
- m = 365
- R = 365ln ( 1 + 0.05/365 ) = 0.049995
- Notice that as m increases, the difference between the rates decreases.
- EXAMPLE: Discrete compounding rate
- A loan is quoted at 12% annually with continuous compounding. Interest is paid monthly. Calculate the equivalent rate with monthly compounding.
- R = 12 (e^0.12/12 -1) = 12.06%
- EXAMPLE:
- What is the continuously compounded rate of return for an investment that has a value today of $86.50 and will have a future value of $100 in one year?
- FV = Ae ^ R*n
- 100 = 86.50 * e ^ R*1
- 100 / 86.50 = e^R
- 1.156069 = e^R
- ln(1.156069) = R
- 14.50% = R
Spot Rates
- Spot rates are the rates that correspond to zero-coupon bond yields.
- They are the appropriate discount rates for a single cash low at a particular future time or maturity.
- Spot rates are also often called zero rates.
- Most interest rates that are observed in the market, such as coupon bond yields, are not spot rates.
Bond Pricing
- A coupon bond makes a series of cash flows.
- Each cash low considered in isolation is equivalent to a zero-coupon bond.
- Using this interpretation, a coupon bond is a series of zero-coupon bonds.
- Formula for Non Continous:
- PV = (( CR / t ) / (1 + (r1/t)^1 ) + (( CR / t ) / (1 + (r2/t)^2 ) + .. + (( CR / t ) / (1 + (rn/t)^n )
- CR = Coupon Rate
- t = Frequency eg: Semiannually, Annually, Quarterly
- r = Bond equivalent spot rate that corresponds to n periods
- n = Maturity in years
- Formula for Continous:
- PV = (( CR / t ) e^-(r1/t)*1 ) + (( CR / t ) e^-(r2/t)*2 ) + .. + (( CR / t ) e^-(rn/t)*n )
- Notice that the two discounting approaches will produce a similar result.
Bond Yield
- Bond yield is a return an investor expects to receive on their investment in a bond. It essentially reflects the annualized interest you'll earn on a bond if you hold it until maturity (when the principal amount is repaid).
- The yield of a bond is the single discount rate determined based on its current market price and the present value of its future cash flows (coupon payments and principal repayment).
- Yield of a Bond:
- The yield of a bond, often referred to as the yield to maturity (YTM), is the total return an investor can expect to earn if the bond is held until maturity.
- It represents the annualized return on investment considering both the periodic coupon payments and any gain or loss upon maturity if the bond is purchased at its current market price.
- Single Discount Rate:
- The "single discount rate" mentioned in the line is the yield to maturity (YTM).
- It is the discount rate that, when applied to all future cash flows (coupon payments and principal repayment), equates their present value to the current market price of the bond.
- In other words, it's the rate at which the sum of the present values of all future cash flows equals the bond's current price.
- Equates the Present Value:
- The present value of a bond's cash flows is calculated by discounting each cash flow (coupon payments and principal repayment) at the yield to maturity.
- When you discount all these future cash flows at the yield to maturity, the sum of these present values should equal the current market price of the bond.
- Implication:
- This relationship is crucial in bond pricing and valuation.
- If the bond is priced lower than its face value (at a discount), the yield to maturity will be higher than the coupon rate because investors will earn more on their initial investment due to the bond's appreciation to par value at maturity.
- Conversely, if the bond is priced higher than its face value (at a premium), the yield to maturity will be lower than the coupon rate because investors will receive less than they paid at maturity.
- Example:
- Compute the yield for the bond.
- FV = $100
- N = 4 which is 2 years
- PV = -102.14
- CR = 4% semiannual
- PMT = 2 which is calculated from FV and CR and its semiannaul hence div by 2 = 100 * 4% / 2
- Answer
- CPT using calculator -> I/Y = 1.446%
- YTM = 1.446% * 2 = 2.89%
- The bond’s par yield is the rate that makes the price of a bond equal to its par value. When the bond is trading at par, the coupon will be equal to the bond’s yield.
- Bond's Par Yield:
- The par yield of a bond is the coupon rate (annual interest rate) that makes the bond's price equal to its par value.
- Par value, also known as face value, is the nominal value of a bond that is typically repaid to the bondholder at maturity.
- When the bond's price in the market is exactly equal to its par value, the coupon rate (par yield) is the rate at which the annual coupon payments (interest payments) are exactly equal to the interest yield that investors receive based on the bond's current market price.
- Bond Trading at Par:
- When a bond is trading at par, it means the market price of the bond equals its par value.
- For example, if a bond has a par value of $1,000 and is trading at $1,000, it is trading at par.
- In this scenario, the coupon rate (par yield) is the same as the bond's current yield, which is the annual coupon payment divided by the bond's current market price (expressed as a percentage).
- Implication:
- When the bond trades at par, the coupon rate (par yield) determines the rate of return for investors who buy the bond at that price.
- The coupon payments received by the investor over the bond's life, when discounted at the bond's yield to maturity (YTM), will exactly equal the bond's current market price.
- Investors who purchase the bond at par will receive coupon payments that match the yield implied by the bond's market price, making the bond's total return consistent with its coupon rate when it is trading at par.
- In summary, the statement explains that the par yield of a bond is the coupon rate that aligns its market price with its par value.
- When the bond is trading at par, the coupon rate is exactly equal to the bond's yield, ensuring that the bond's price reflects its nominal value and the investor's return matches the coupon payments received.
Bootstrapping Spot Rates
- Bootstrapping spot rates refers to a method used in finance to derive the zero-coupon yield curve from the prices of fixed-income securities, such as bonds or swaps, with varying maturities.
- Steps in Bootstrapping Spot Rates:
- Understanding Spot Rates:
- Spot rates (or zero-coupon rates) are the interest rates for a specific maturity date, which can be derived from the prices of bonds that provide cash flows at various points in time.
- Starting Point:
- Begin with the prices of bonds or other fixed-income securities available in the market.
- These securities will have different maturity dates and corresponding market prices.
- Identifying Cash Flows:
- For each bond or security, identify the cash flows it promises over its lifetime.
- This typically includes periodic coupon payments and the principal repayment at maturity.
- Reverse Engineering:
- To bootstrap the spot rates, work backward from the securities with the shortest maturities to those with longer maturities.
- Start with the shortest maturity instrument, often a cash deposit or a very short-term bond, which effectively has only one cash flow (the principal and possibly a single coupon payment).
- Calculation Process:
- Calculate the spot rate for the first maturity (the shortest) by solving for the rate that equates the present value of its cash flows to its market price.
- This rate is often referred to as the zero-coupon rate for that maturity.
- Use this spot rate to discount the cash flows of the next longer maturity instrument (which typically has more than one cash flow). This will provide the implied spot rate for the next maturity.
- Continue this process iteratively, using each newly derived spot rate to value the cash flows of the next longer maturity instrument.
- Iterative Adjustment:
- Each step involves adjusting the spot rate until the present value of all cash flows matches the observed market price of the bond.
- This iterative process ensures that the spot rates derived are consistent with the market prices of the bonds being used as inputs.
- Yield Curve Construction:
- After bootstrapping all spot rates for various maturities, you obtain a yield curve that plots these spot rates against their respective maturities.
- This yield curve is crucial in finance for pricing other financial instruments, such as swaps, futures contracts, and options, as well as for making investment decisions and risk management.
- In conclusion, bootstrapping spot rates is a fundamental technique in finance for deriving the term structure of interest rates from market prices of bonds and other fixed-income securities, enabling precise valuation and risk assessment in financial markets.
FR and FRA
Forward Rate
- Forward rates are interest rates implied by the spot curve for a speciied future period.
- Recall that spot rates are the appropriate rates that an investor should expect to realize for various maturities.
- Suppose an investor is faced with the following two investments, which are based on the spot curve.
- Invest for two years at 2.915%.
- Invest for a year at 2.136%, and then roll over that investment for another year at the forward rate.
- It does not matter which investment is chosen if they both offer the same return at the end of two years.
- This is the same as stating that both strategies give the same future value at the end of two years.
- Formula : Equating the two future values
- e^( (r2/t)*(n2*t) ) = (e^( (r1/t)*(n2*t) )) * (e^FR/t*n)
- r1 and r2 = spot rate of years 1 and 2 respectively
- FR = forward rate
- n = number of years
- t = frequence
- Formula : Calculate FR by using the following equation (which assumes continuously compounded rates)
- FR = R2T2 - R1T1 / T2 - T1
Forward Rate Agreements
- A forward rate agreement (FRA) is a forward contract obligating two parties to agree that a certain interest rate will apply to a principal amount during a specified future time.
- Obviously, forward rates play a crucial role in the valuation of FRAs.
- The T2 cash flow of an FRA that promises the receipt or payment of Rk is:
- cash flow (if receiving Rk) = L * (Rk - R) * (T2 - T1)
- cash flow (if paying Rk) = L * (R - Rk) * (T2 - T1)
- here:
- L = principal
- Rk = annualized fixed rate, expressed with compounding period T2 - T1
- R = annualized floating rate, expressed with compounding period T2 - T1
- Ti = time i, expressed in years
- Example:
- Suppose an investor has entered into an FRA where he has contracted to pay a fixed rate of 3% on $1 million based on the quarterly rate in three months. Assume that rates are compounded quarterly. Compute the payoff from the FRA if the quarterly rate is 1% in three months.
- cash flow (if paying Rk) = L * (R - Rk) * (T2 - T1)
- Rk = 3%
- L = $1million
- R = 1%
- $1,000,000(0.01 - 0.03)(.25)
- For this FRA, the payoff will take place in six months. The net payoff will be the difference between the fixed-rate payment and the floating rate receipt. If the floating rate is 1% in three months, the payoff at the end of the sixth month will be $5000.
- The value of an FRA if receiving or paying the fixed interest rate is:
- Example:
- Suppose the three-month and six-month floating rates are 4% and 5%, respectively (continuously compounded rates). An investor enters into an FRA in which she will receive 8% (assuming quarterly compounding) on a principal of $5,000,000 between Months 3 and 6. Calculate the payoff from the FRA.
- 3 months quarter floating rates (continously compounded rates) = 4%
- 6 months quarter floating rates (continously compounded rates) = 5%
- L = $5,000,000
- Fixed rates (quarterly compounding) = 8%
- FR = 0.05 + (0.05 - 0.04) * (1/ 2 -1) = 0.06 = 6%
- FR (quarterly compounding) = 4 * ((e ^ 0.06/4) - 1) = 0.060452 = 6.05%
- payoff =
- $51,000,000(0.08 - 0.060452)(.50 - .25) / 1 + 0.05 * (0.50 - 0.25)
- $24,074
Term Structure Theory
- Market segmentation theory
- The market segmentation theory states that the bond market is segmented into different maturity sectors and that supply and demand for bonds in each maturity range dictate rates in that maturity range.
- The market segmentation theory does not fully make sense because many investors are more likely to move between the maturity sector based on the attractiveness of the available yields.
- Expectations theory
- The expectations theory suggests that forward rates correspond to expected future spot rates.
- That is, forward rates are good predictors of expected future spot rates.
- An expectation of rising (falling) interest rates would suggest an upward-sloping (downward-sloping) yield curve.
- In reality, the expectations theory may be in doubt because upward-sloping yield curves occur far more frequently than downward-sloping and a logical expectation would be for upward- and downward-sloping curves to occur with equal frequency. Here the people expectations would be logical 50/50 chances.
- Liquidity preference theory
- In general behaviour,
- borrower would want money for longer duration
- but lender would want money money back in short duration
- in this theory as the lender is taking the risk he/she would be paid higher interest of longer than shorter, which leads to upward slope.
- The liquidity preference theory attempts to clear up the doubt with the expectations theory.
- Liquidity preference suggests that most depositors prefer short-term liquid deposits to meet current needs.
- In order to coax them to lend/invest longer term, the intermediary will raise longer-term rates by adding a liquidity premium.
Duration of a Bond
- Duration means on average during how much time the bond holder gets his money back.
- Average time taken by the bond holder to receive his money back
- For zero coupon bond the duration is simply the time to maturity
- For coupon bond its duration will be necesarily shorter than its maturity
- Formula to calculate duration is:
- The usefulness of the duration measure lies in the fact that the approximate change in a bond’s price, B, for a parallel shift in the yield curve of Δy is:
- ΔB / B = -duration * Δy
- The change in yield is often expressed as a basis point change. One basis point is equivalent to 0.01%. So a 100 basis point change is a change of 1% in the yield.
- When yields are continuously compounded, the provided duration measure is known as Macaulay duration.
- Modified duration is used when the yield given is something other than a continuously compounded rate. When the yield is expressed as a semiannually compounded rate, for example, modified duration = duration / (1 + y/2).
- Just to reiterate, to calculate the approximation of change in a bond's price:
- for non continuously compounding rate is using modified duration
- for continuously compounding rate is using Macaulay duration
- Note that as m goes to infinity (continuous compounding), the two measures are equal and there is no difference between the two.
- Dollar duration is simply modified duration multiplied by the price of the bond.
Convexity
- So far so good, duration is a good approximation of price changes for an option-free bond, but it’s only good for relatively small changes in interest rates.
- As rate changes grow larger, the curvature of the bond price/yield relationship becomes more important, meaning that a linear estimate of price changes, such as duration, will contain errors.
- In fact, the relationship between bond price and yield is not linear (as assumed by duration) but convex.
- This convexity shows that the difference between actual and estimated prices widens as the yield swings grow.
- That is, the widening error in the estimated price is due to the curvature of the actual price path. This is known as the degree of convexity.
- In order to obtain an estimate of the percentage change in price due to convexity, or the amount of price change that is not explained by duration, the following calculation will need to be made:
- Convexity formula is derived through calculus.
- To calculate the approximation of the change in a bond's price:
- ΔB / B = -duration * Δy + convexity effect



















