- Effective rate of interest (i)
- The rate earned over one period on the balance at the START of the period: 1 grows to 1+i after one period.
- Effective rate of discount (d)
- The rate applied to the END-of-period balance: d=1+ii=1−v=iv.
- Discount factor (v)
- The present value of 1 due in one period: v=1+i1=1−d.
- Present value of 1 in n periods
- vn=(1+i)−n.
- Accumulated value of 1 in n periods
- (1+i)n under compound interest.
- Simple interest accumulation
- a(t)=1+it: interest is earned only on the original principal, never on prior interest.
- Compound interest accumulation
- a(t)=(1+i)t: interest earns interest. Exam FM is compound unless told otherwise.
- Accumulation function a(t)
- The accumulated value at time t of 1 invested at time 0. Under compound interest a(t)=(1+i)t.
- Nominal rate of interest i⁽ᵐ⁾
- An annual rate convertible m times a year; each subperiod earns i(m)/m. Effective annual rate =(1+i(m)/m)m−1.
- Nominal rate of discount d⁽ᵐ⁾
- Convertible m times a year; 1+i=(1−md(m))−m.
- Effective annual rate from i⁽ᵐ⁾
- i=(1+mi(m))m−1. More frequent compounding raises the effective rate.
- Force of interest (δ)
- The instantaneous, continuously compounded rate. For a constant force, accumulation over t years is eδt, and δ=ln(1+i).
- Relationship e^δ
- eδ=1+i, so v=e−δ and δ=ln(1+i).
- Varying force of interest accumulation
- a(t)=exp(∫0tδ(s)ds).
- Force of interest from a(t)
- δ(t)=a(t)a′(t)=dtdlna(t).
- Equation of value
- Set the value of all inflows equal to the value of all outflows at a single chosen comparison date, after discounting/accumulating each cash flow to it.
- Discounting vs accumulating
- Discount a future payment back by multiplying by vt; accumulate a deposit forward by multiplying by (1+i)t.
- Ordering: i, i⁽ᵐ⁾, δ, d⁽ᵐ⁾, d
- For a fixed effective rate: d<d(m)<δ<i(m)<i. The force δ sits between the nominal discount and nominal interest rates.
- v and d relationship
- v=1−d; the discount factor is one minus the discount rate.
- Doubling time (constant force)
- Solve eδt=2, so t=δln2.
- Rule of 72 (intuition)
- A balance roughly doubles in 72/(100i) years; an approximation, exact doubling uses ln2÷ln(1+i).
- Effective rate over a non-unit period
- Over period [a,b], the effective rate is a(a)a(b)−a(a).
- Present value
- The value today of one or more future cash flows, found by discounting each at the appropriate rate.
- Accumulated value
- The value at a future date of one or more cash flows, found by accumulating each forward at the appropriate rate.
- Interest in the t-th period a(t) − a(t−1)
- The amount of interest earned in period t on an investment of 1 is a(t)−a(t−1).
- Convert force δ to discount factor
- v=e−δ; to discount n years, multiply by e−δn.
- Continuous compounding limit
- As m → ∞, (1+mi(m))m→eδ=1+i.
- Why d < i for the same effective rate
- Discount is taken off the larger end-of-period amount, so a smaller rate d achieves the same effect as interest rate i on the smaller starting amount.
- Effective vs nominal: which is bigger?
- For a positive nominal rate, the effective annual rate exceeds the nominal rate whenever m > 1 (more than one compounding per year).
- Present value of a single payment C in n periods
- PV=Cvn=(1+i)nC.
- Annuity-immediate
- Level payments at the END of each period. Present value an∣=i1−vn.
- Annuity-due
- Level payments at the START of each period. Present value a¨n∣=d1−vn=an∣(1+i).
- Relationship between ä and a
- a¨n∣=an∣(1+i): each due payment lands one period earlier.
- Accumulated value, annuity-immediate
- sn∣=i(1+i)n−1.
- Accumulated value, annuity-due
- s¨n∣=sn∣(1+i)=d(1+i)n−1.
- PV–AV relationship
- sn∣=an∣(1+i)n: the accumulated value is the present value rolled forward n periods.
- Perpetuity-immediate
- Pays 1 at the end of each period forever; present value =i1.
- Perpetuity-due
- Pays 1 at the start of each period forever; present value =d1.
- Deferred annuity
- Value the annuity one period before its first payment, then discount over the deferral: k∣an∣=vkan∣.
- Increasing annuity-immediate (Ia)ₙ
- Payments 1, 2, …, n at period ends: (Ia)n∣=ia¨n∣−nvn.
- Decreasing annuity-immediate (Da)ₙ
- Payments n, n−1, …, 1 at period ends: (Da)n∣=in−an∣.
- Increasing perpetuity-immediate
- Payments 1, 2, 3, … forever: present value =i21+i. It also equals i1+i21.
- Geometric (growing) annuity
- First payment P, growing at g per period, n payments: PV=P⋅i−g1−(1+i1+g)n (for g=i).
- Growing perpetuity
- First payment P, growing at g forever (g < i): PV=i−gP.
- Continuous annuity
- Paid continuously at rate 1 per period: aˉn∣=δ1−vn.
- Continuously increasing annuity (Iˉaˉ)n∣
- (Iˉaˉ)n∣=δaˉn∣−nvn.
- m-thly payable annuity-immediate an∣(m)
- Payments of 1/m at the end of each m-thly subperiod: an∣(m)=i(m)1−vn.
- Finding the number of payments n
- From PV=Pan∣, solve vn=1−Pi⋅PV, then n=lnvln(vn).
- Finding the unknown rate i
- An annuity equation in i has no closed form; solve numerically (calculator I/Y key) or by interpolation.
- Level payment from a present value
- P=an∣PV: divide the present value by the annuity-immediate factor.
- Difference: due value minus immediate value
- a¨n∣−an∣=an∣⋅i (in present-value terms, the immediate value times i).
- Annuity-immediate vs annuity-due timing
- Immediate: first payment at time 1, last at time n. Due: first payment at time 0, last at time n−1.
- Perpetuity with first payment deferred
- Value the perpetuity one period before its first payment, then discount: e.g. first payment at time k+1 → vk⋅i1.
- Annuity payable less frequently than interest converts
- Adjust by converting the interest rate to the payment period's effective rate first, then apply the standard annuity factor.
- Accumulated value of a deferred annuity
- The deferral does not change the accumulated value at the end of the payment stream; only the present value is discounted by the deferral.
- Outstanding stream as an annuity
- Any level future cash-flow stream of n payments is valued with an∣ — the engine behind loans and bonds.
- (Is)n∣ increasing accumulated annuity
- (Is)n∣=is¨n∣−n.
- Sum check: aₙ + level payment recovers PV
- If you discount each of the n level payments by vt and add, you recover Pan∣ — the annuity factor is just that sum.
- Payment timing keyword 'first payment now'
- Signals an annuity-DUE; the first payment is at time 0.
- Payment timing keyword 'first payment in one year'
- Signals an annuity-IMMEDIATE; the first payment is at time 1.
- Loan amortization method
- Each level payment covers interest on the balance first, then repays principal. L=Pan∣.
- Level loan payment
- P=an∣L for a loan L repaid with n level payments at rate i.
- Interest portion of payment t
- It=iBt−1=P(1−vn−t+1), where Bt−1 is the prior balance.
- Principal portion of payment t
- Pt=Pvn−t+1. It grows geometrically: Pt+1=Pt(1+i).
- Outstanding balance — prospective
- Present value of the remaining payments: Bt=Pan−t∣.
- Outstanding balance — retrospective
- Loan accumulated minus payments accumulated: Bt=L(1+i)t−Pst∣.
- Prospective = retrospective
- For a level-payment loan the two methods give the same outstanding balance at every time t.
- Sinking-fund method
- Borrower pays the lender interest iL each period and deposits into a fund (rate j) that accumulates to L. Total outlay =iL+sn∣jL.
- Sinking-fund deposit
- D=sn∣jL, where j is the sinking-fund rate.
- Sinking-fund balance after k deposits
- Dsk∣j: the deposits accumulated at the fund rate j.
- Total interest paid over a loan's life
- Sum of all payments minus the original principal: nP−L.
- Principal repaid grows by (1+i)
- In a level-payment loan, Pt+1=Pt(1+i); the final payment is almost all principal.
- Interest in the first payment
- I1=iL: interest on the full original balance.
- Refinancing a loan
- Find the outstanding balance at the refinance date (PV of remaining payments at the old rate), then amortize that balance over the new term at the new rate.
- Amortization schedule columns
- Payment, interest paid (iBt−1), principal repaid (payment − interest), and new balance (Bt−1−Pt).
- When does the sinking-fund method cost more?
- When the sinking-fund rate j is below the loan rate i, because the fund earns less than the interest charged on the full balance.
- Balance just after vs just before a payment
- Just before payment t the balance is Bt−1(1+i); just after it is Bt=Bt−1(1+i)−P.
- Combined principal in payments t and t+1
- Pt+Pt+1=P(vn−t+1+vn−t); use the geometric growth of principal.
- Loan with non-level payments
- Use the retrospective method (or first principles), since the prospective annuity factor assumes level payments.
- Final payment / balloon adjustment
- If level payments don't exactly clear the loan, a smaller (or drop) final payment settles the residual balance.
- Bond price formula (basic)
- P=Fran∣+Cvn: present value of coupons plus present value of redemption, at the yield rate.
- Bond price (premium/discount form)
- P=C+(Fr−Ci)an∣: redemption value plus the present value of the coupon-vs-yield difference.
- Coupon amount
- Fr: the face amount F times the coupon rate r. The coupon is fixed for the bond's life.
- Premium bond
- Coupon rate > yield rate → price > redemption value. The premium P−C is written down each period.
- Discount bond
- Coupon rate < yield rate → price < redemption value. The discount C−P is accumulated (written up) each period.
- Par bond
- Coupon rate = yield rate → price equals the redemption value exactly.
- Book value
- The present value of a bond's remaining cash flows at the ORIGINAL yield rate; it glides to the redemption value C at maturity.
- Write-down of premium in period t
- Coupon minus yield-rate interest: Fr−iBt−1. It reduces the book value toward C.
- Write-up of discount in period t
- Yield-rate interest minus the coupon: iBt−1−Fr. It increases the book value toward C.
- Interest earned in period t (bond)
- iBt−1: the yield rate applied to the start-of-period book value.
- Zero-coupon bond price
- Only one cash flow: P=Cvn=(1+i)nC. All return comes from the price-to-redemption growth.
- Yield to maturity (YTM)
- The single yield rate i that equates the bond's price to the present value of its coupons plus redemption.
- Discount price ⇒ yield vs coupon
- A bond bought below redemption value (discount) has a yield ABOVE its coupon rate; a premium price gives a yield below the coupon.
- Accrued interest
- The seller's earned share of the next coupon when sold between coupon dates: (fraction of period elapsed)×Fr.
- Clean (market) price
- The quoted price: clean=dirty−accrued interest.
- Dirty (full) price
- The cash actually paid: dirty=clean+accrued interest.
- Callable bond — premium
- Coupon > yield: price to the EARLIEST call date (worst for the holder) to guarantee at least the desired yield.
- Callable bond — discount
- Coupon < yield: price to the LATEST possible redemption date (lowest price) to guarantee at least the desired yield.
- Makeham's formula
- P=K+ig(C−K), where K=Cvn is the PV of redemption and g=Fr/C is the modified coupon rate.
- Modified coupon rate g
- g=CFr: the coupon as a fraction of the redemption value, used in Makeham's formula.
- Redemption value C
- The amount paid at maturity. If redeemable at par, C=F; otherwise C may differ from the face amount.
- Face (par) value F
- The amount used with the coupon rate to compute the coupon Fr. It need not equal the price or the redemption value.
- Why a premium amortizes down
- Each coupon exceeds the yield-rate interest, so the surplus reduces book value until it reaches C at maturity.
- Salvage / redemption at a premium
- If C > F (redeemable above par), the redemption term Cvn in the price formula uses C, not F.
- Bond sold before maturity
- Its sale price is the present value of the remaining coupons and redemption at the buyer's required yield at that time.
- Total accumulated premium amortized
- Over the bond's life the premium written down sums to P−C; the discount written up sums to C−P.
- Coupon vs yield: price direction
- Higher yield → lower price (inverse relationship), holding coupons and term fixed.
- Semiannual coupons
- Use the per-period (e.g. semiannual) coupon, the per-period yield, and the number of half-years as n in the price formula.
- Bond amortization schedule
- Tracks coupon, interest earned (iBt−1), premium/discount adjustment, and the new book value each period.
- Current yield vs YTM
- Current yield = annual coupon ÷ price (ignores capital gain/loss); YTM accounts for the price-to-redemption change too.
- Net present value (NPV)
- Sum of all cash flows discounted at the required rate: NPV=∑tCFtvt. Accept the project if NPV > 0.
- Internal rate of return (IRR)
- The single rate that makes NPV = 0: ∑tCFt(1+r)−t=0.
- NPV vs IRR decision rule
- NPV>0⟺IRR> required rate. Both accept the same projects for a simple cash-flow sign pattern.
- Multiple IRRs
- A cash-flow stream whose sign changes more than once can have more than one IRR; rely on NPV in that case.
- Dollar-weighted rate of return
- The fund's IRR — sensitive to the size and timing of deposits/withdrawals. Simple-interest approx: interest ÷ exposure-weighted balance.
- Time-weighted rate of return
- Product of subperiod growth factors between cash flows, minus 1: ∏k(1+jk)−1. Removes timing effects.
- Dollar- vs time-weighted: which for a manager?
- Use TIME-weighted to judge the manager's skill (timing-neutral); use dollar-weighted for the investor's actual experience.
- Simple-interest dollar-weighted approximation
- i≈A+∑tCt(1−t)I: interest over the exposure-weighted average balance.
- Macaulay duration
- PV-weighted average time of cash flows: DMac=∑tvtCFt∑ttvtCFt.
- Modified duration
- Price sensitivity to yield: Dmod=1+iDMac. Then PΔP≈−DmodΔi.
- Duration of a zero-coupon bond
- Equals its time to maturity n, because there is a single cash flow at time n.
- Macaulay duration formula via aₙ (level)
- For a level annuity, duration is a PV-weighted average of payment times; longer streams and lower rates raise duration.
- First-order price approximation
- P(i+Δi)≈P(i)(1−DmodΔi). Linear; understates the price for large moves.
- Convexity
- The second-order measure of curvature of the price-yield curve; adding it corrects the duration estimate for large rate changes.
- Second-order price approximation
- PΔP≈−DmodΔi+21Conv(Δi)2.
- Why duration matters
- Higher duration = greater interest-rate risk; a small yield change moves the price more for a high-duration asset.
- Redington immunization
- Three conditions at the valuation rate: PVA=PVL, DA=DL, and CA>CL (asset convexity greater).
- Redington — meaning of each condition
- Equal PVs ⇒ surplus zero; equal durations ⇒ first derivative of surplus zero; greater asset convexity ⇒ surplus at a local minimum.
- Full immunization
- A liability is bracketed by asset cash flows before and after it, protecting against any single shift (not just small ones).
- Cash-flow matching
- Fund each liability with an asset cash flow of identical date and amount; eliminates reinvestment and rate risk with no rebalancing.
- Immunization vs cash-flow matching
- Immunization protects against SMALL rate moves and needs rebalancing; cash-flow matching handles any move but is harder to implement.
- Surplus
- Assets minus liabilities, PVA−PVL. Immunization aims to keep surplus ≥ 0 as rates move.
- Reinvestment risk
- The risk that coupons/cash flows must be reinvested at lower-than-expected rates; immunization balances it against price risk.
- Price risk vs reinvestment risk
- Rising rates lower prices (price risk) but raise reinvestment income; at the duration horizon the two offset — the basis of immunization.
- Portfolio yield rate
- A single equivalent rate solving the portfolio's equation of value; the portfolio's overall IRR.
- Reinvestment of annuity payments
- If payments earn a different reinvestment rate, accumulate them at that rate separately, then combine with the rest of the stream.
- Duration of a portfolio
- The market-value-weighted average of the durations of its components.
- Convexity is always positive for option-free bonds
- Standard fixed cash-flow bonds have positive convexity, so duration always understates the price after a yield move (a favorable bias).
- Effect of higher coupon on duration
- Higher coupons shorten duration (more value arrives early); lower coupons and longer maturities lengthen it.
- Discounted payback / project measures
- Beyond NPV and IRR, exams may ask for the discounted payback period — the time for discounted inflows to recover the outlay.
- Spot rate
- Today's annual yield on a single cash flow paid at one future date t; discount by (1+st)−t.
- Forward rate
- An interest rate agreed today for a future period, derived from spot rates by no-arbitrage.
- Forward rate from spot rates
- (1+s2)2=(1+s1)(1+f1,2), so f1,2=1+s1(1+s2)2−1.
- General forward-rate relationship
- (1+sn)n=(1+sm)m(1+fm,n)n−m for the forward rate covering periods m to n.
- Yield curve
- A plot of spot rates against time to maturity at a single point in time.
- Normal (upward-sloping) term structure
- Long-term spot rates exceed short-term rates; the yield curve rises with maturity.
- Inverted term structure
- Short-term spot rates exceed long-term rates; the yield curve falls with maturity.
- Discount factor from spot rate
- Pt=(1+st)−t: the price today of 1 paid at time t.
- Pricing a cash flow off the term structure
- Discount each future cash flow by its OWN spot-rate discount factor Pt, not a single flat rate.
- Interest rate swap
- A contract to exchange a stream of FIXED interest payments for a stream of FLOATING payments on a notional amount; the notional is never exchanged.
- Notional amount
- The principal used only to compute the swap's interest payments; it is not itself paid between counterparties.
- Swap rate
- The level fixed rate setting the swap's initial value to zero: R=∑t=1nPt1−Pn.
- Two-year swap rate example
- With P1=1.03−1,P2=1.04−2: R=P1+P21−P2≈3.98%.
- Purpose of a swap
- To convert floating-rate exposure into fixed (or vice versa) without trading the underlying debt.
- Deferred swap
- A swap whose settlement payments start at a future date; the swap rate uses only the discount factors for the active settlement dates.
- Swap value after inception
- Re-value the fixed and floating legs off the current term structure; their difference is the swap's current value.
- Components of an interest rate
- A quoted rate = real risk-free rate + inflation premium + default-risk premium + liquidity premium + maturity/term premium.
- Real vs nominal interest rate
- The nominal rate includes expected inflation; the real rate strips it out: roughly real≈nominal−inflation.
- Default-risk premium
- Extra yield demanded for the chance a borrower fails to pay; higher for riskier issuers.
- Liquidity premium
- Extra yield for holding an asset that is harder to sell quickly without a price concession.
- Term (maturity) premium
- Extra yield typically demanded for longer maturities, contributing to an upward-sloping yield curve.
- Supply and demand for loanable funds
- Equilibrium interest rates are set where the supply of savings meets the demand for borrowing; shifts move rates.
- Central-bank policy and rates
- Monetary policy (e.g. setting short-term target rates) shapes the short end of the yield curve and influences the whole term structure.
- Each point on the yield curve
- Represents the interest rate for a particular term to maturity at a single moment in time.
- No-arbitrage principle
- Two strategies with identical cash flows must have the same price today; it pins down forward and swap rates from spot rates.
- Bootstrapping spot rates
- Deriving spot rates sequentially from the prices of coupon bonds or par yields, shortest maturity first.
- Par yield
- The coupon rate at which a bond prices at par given the current spot curve; closely related to the swap rate.
- Floating leg of a swap
- Payments tied to a reference rate that resets each period; its value at inception equals the notional minus the final discount factor times notional.
- Fixed leg of a swap
- Level payments at the swap rate R; valued as R×∑tPt times the notional.
- Inflation premium
- The portion of a nominal rate compensating lenders for expected loss of purchasing power.
- Comparison date (focal date)
- The single point in time to which all cash flows are moved when writing an equation of value; the answer is the same whichever date you choose.
- Equivalent rates
- Two rates are equivalent if they produce the same accumulated value over the same period, e.g. i, i(m), d, and δ describing one investment.
- Accumulation vs amount function
- a(t) is the accumulation of 1; the amount function A(t)=ka(t) accumulates an initial investment k.
- Effective rate in period n
- in=a(n−1)a(n)−a(n−1): interest earned in period n relative to the start-of-period balance.
- Sinking fund vs amortization equivalence
- If the sinking-fund rate equals the loan rate, the sinking-fund method costs exactly the same as amortization.
- Outstanding balance recursion
- Bt=Bt−1(1+i)−P: grow the balance by interest, then subtract the payment.
- Coupon-bond price between dates
- Accumulate the previous coupon-date price forward by the partial-period interest, then subtract any coupon just paid (for the dirty price).
- Effective yield on a bond bought at a discount
- Exceeds the coupon rate because the investor also earns the capital gain from price to redemption value.
- Annuity-immediate factor as a geometric sum
- an∣=v+v2+⋯+vn=1−vv(1−vn)=i1−vn.
- Annuity-due factor as a geometric sum
- a¨n∣=1+v+⋯+vn−1=1−v1−vn=d1−vn.
- Convexity sign for fixed cash flows
- Positive — the price-yield curve is convex, so prices fall less and rise more than a linear duration estimate predicts.
- Choosing assets to immunize
- Pick assets whose duration matches the liability duration while keeping greater convexity, after matching present values.
- Yield rate of a cash-flow stream
- The IRR — the rate equating the present value of inflows to the present value of outflows.
- Net cash flow
- Inflows minus outflows in a period; the sign of the net cash flow sequence affects whether a unique IRR exists.
- Reinvested coupons accumulation
- If reinvested at rate j ≠ i, accumulate coupons with sn∣j and add the redemption to get the total accumulated value.
- Price of 1 paid at time t (Pₜ)
- The discount factor from the spot curve: Pt=(1+st)−t; the building block for swap and bond valuation.
- Swap as a series of forwards
- A swap can be decomposed into a portfolio of forward rate agreements; its fair fixed rate is a discount-factor-weighted average of forward rates.
- Level vs varying interest over time
- When rates vary by period, discount each cash flow with the product of the relevant one-period factors rather than a single vt.
- Accumulated value with reinvestment at a second rate
- Split into the stream's own growth plus the separately-accumulated reinvested interest, then sum at the horizon.
- Loan interest savings from extra payments
- An extra principal payment reduces all future interest because subsequent interest is charged on a smaller balance.
- Bond yield approximation
- When no closed form exists, estimate the yield by interpolation between two trial rates that bracket the price.
- Continuous force vs effective rate
- δ=ln(1+i)<i for i>0: the force of interest is always below the effective annual rate.
- Annuity symbol an∣i meaning
- Present value, one period before the first of n level payments of 1, valued at rate i.
- Sinking-fund total cost vs amortization
- Equal when fund rate = loan rate; the sinking-fund method costs more when the fund earns less than the loan rate.
- Book value at issue equals price
- At purchase the book value equals the purchase price; it then amortizes toward the redemption value C.
- Duration as a hedge target
- Setting asset duration equal to the investment horizon (or liability duration) neutralizes first-order interest-rate risk.
- Forward rate vs expected future spot rate
- Under pure expectations they coincide; term and liquidity premiums make forward rates exceed expected future spot rates.
- Why answer every question on Exam FM
- There is no guessing penalty, so an unanswered question is a guaranteed miss; always fill in an answer.
- Calculator TVM keys (BA II Plus)
- N (periods), I/Y (rate per period), PV, PMT, FV — enter four and solve for the fifth to handle most annuity and loan problems.
- Cash-flow worksheet (BA II Plus)
- CF/NPV/IRR keys evaluate uneven cash-flow streams — the fast route to NPV and IRR questions.