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Finance Formulas Cheat Sheet


1. Profitability

Revenue

$$\text{Revenue} = \text{Price per Unit} \times \text{Quantity Sold}$$

Component Definition
Price per Unit The selling price of a single unit ($)
Quantity Sold Number of units sold in the period

Interpretation: Total sales dollars generated before any costs are deducted.
Use case: Measuring top-line growth; sizing a product's market potential.
Example:
A SaaS company charges $120/month per seat and has 800 active seats.
$$\text{Revenue} = $120 \times 800 = $96,000/\text{month}$$


Total Cost

$$\text{Total Cost} = \text{Fixed Costs} + (\text{Variable Cost per Unit} \times \text{Quantity Produced})$$

Component Definition
Fixed Costs Costs unchanged by volume (rent, salaries, insurance)
Variable Cost per Unit Cost incurred for each additional unit (materials, commissions)
Quantity Produced Number of units manufactured or delivered

Interpretation: The sum of all costs at a specific output level.
Use case: Forecasting operating expenses and identifying cost drivers.
Example:
A factory has $50,000/month in fixed costs, $8 variable cost per unit, and produces 10,000 units.
$$\text{Total Cost} = $50,000 + ($8 \times 10,000) = $130,000$$


Gross Profit

$$\text{Gross Profit} = \text{Revenue} - \text{Cost of Goods Sold (COGS)}$$

Component Definition
Revenue Total sales dollars
COGS Direct costs tied to producing the goods sold (materials, direct labor)

Interpretation: Profit remaining after direct production costs; before operating expenses.
Use case: Assessing product-level profitability.
Example:
Revenue = $96,000; COGS (server costs + direct labor) = $32,000
$$\text{Gross Profit} = $96,000 - $32,000 = $64,000$$


Operating Profit (EBIT)

$$\text{Operating Profit} = \text{Revenue} - \text{Operating Costs}$$

Component Definition
Revenue Total sales dollars
Operating Costs COGS + SG&A + R&D — all costs before interest and taxes

Interpretation: Profit from core business operations, before financing costs and taxes.
Use case: Comparing operational efficiency across companies or time periods.
Example:
Revenue = $96,000; Operating costs (COGS + salaries + marketing) = $74,000
$$\text{Operating Profit} = $96,000 - $74,000 = $22,000$$


Net Profit

$$\text{Net Profit} = \text{Revenue} - \text{Total Expenses (including interest and taxes)}$$

Component Definition
Revenue Total sales dollars
Total Expenses Operating costs + interest expense + income taxes

Interpretation: The bottom-line profit belonging to shareholders after every obligation.
Use case: Evaluating overall company profitability; basis for EPS and dividends.
Example:
Revenue = $96,000; Operating costs = $74,000; Interest = $1,500; Taxes = $4,200
$$\text{Net Profit} = $96,000 - ($74,000 + $1,500 + $4,200) = $16,300$$


Contribution Margin per Unit

$$\text{CM per Unit} = \text{Price per Unit} - \text{Variable Cost per Unit}$$

Component Definition
Price per Unit Revenue received for selling one unit
Variable Cost per Unit Cost incurred to produce one additional unit

Interpretation: The dollar amount each unit sold contributes toward covering fixed costs and generating profit.
Use case: Pricing decisions; understanding how volume changes affect profit.
Example:
A smartphone accessory sells for $25; materials + packaging = $9/unit
$$\text{CM per Unit} = $25 - $9 = $16$$


Gross Margin %

$$\text{Gross Margin %} = \frac{\text{Revenue} - \text{COGS}}{\text{Revenue}} \times 100 = \frac{\text{Gross Profit}}{\text{Revenue}} \times 100$$

Component Definition
Numerator Gross Profit = revenue minus direct production costs
Denominator Revenue = total sales dollars

Interpretation: What percentage of each sales dollar remains after paying for what was sold.
Use case: Benchmarking product margins against competitors; tracking pricing power.
Example:
Revenue = $96,000; COGS = $32,000
$$\text{Gross Margin %} = \frac{$96,000 - $32,000}{$96,000} = \frac{$64,000}{$96,000} = 66.7%$$


Operating Margin %

$$\text{Operating Margin %} = \frac{\text{Operating Profit (EBIT)}}{\text{Revenue}} \times 100$$

Component Definition
Numerator Operating Profit (EBIT) — profit after all operating costs
Denominator Revenue = total sales dollars

Interpretation: What percentage of each sales dollar remains after all operating costs.
Use case: Comparing cost efficiency across companies regardless of financing choices.
Example:
Operating Profit = $22,000; Revenue = $96,000
$$\text{Operating Margin %} = \frac{$22,000}{$96,000} = 22.9%$$


Net Margin %

$$\text{Net Margin %} = \frac{\text{Net Profit}}{\text{Revenue}} \times 100$$

Component Definition
Numerator Net Profit — after all expenses, interest, and taxes
Denominator Revenue = total sales dollars

Interpretation: Percentage of each sales dollar kept as profit after every cost.
Use case: Comparing overall profitability across industries or time periods.
Example:
Net Profit = $16,300; Revenue = $96,000
$$\text{Net Margin %} = \frac{$16,300}{$96,000} = 17.0%$$


2. Break-Even Analysis

Contribution Margin % (CM Ratio)

$$\text{CM %} = \frac{\text{Price per Unit} - \text{Variable Cost per Unit}}{\text{Price per Unit}} \times 100 = \frac{\text{CM per Unit}}{\text{Price per Unit}} \times 100$$

Component Definition
Numerator CM per Unit = the portion of the selling price not consumed by variable costs
Denominator Price per Unit = full selling price

Interpretation: The fraction of every sales dollar available to cover fixed costs and profit.
Use case: Calculating break-even revenue; pricing sensitivity analysis.
Example:
Price = $25; Variable Cost = $9 → CM per Unit = $16
$$\text{CM %} = \frac{$16}{$25} = 64%$$


Break-Even Units

$$\text{Break-Even Units} = \frac{\text{Total Fixed Costs}}{\text{Contribution Margin per Unit}}$$

Component Definition
Numerator Total Fixed Costs = costs that must be covered regardless of volume
Denominator CM per Unit = profit contribution from selling one additional unit

Interpretation: The exact number of units that must be sold so that total contribution equals total fixed costs (profit = $0).
Use case: Setting minimum sales targets; go/no-go decisions for new products.
Example:
Fixed Costs = $80,000/month; CM per Unit = $16
$$\text{Break-Even Units} = \frac{$80,000}{$16} = 5,000 \text{ units}$$


Break-Even Revenue

$$\text{Break-Even Revenue} = \frac{\text{Total Fixed Costs}}{\text{Contribution Margin %}}$$

Component Definition
Numerator Total Fixed Costs = the dollar amount of overhead to be covered
Denominator CM % = fraction of each revenue dollar that contributes to covering fixed costs

Interpretation: The total sales dollars required to cover all fixed costs with zero profit remaining.
Use case: Revenue planning and scenario analysis when unit prices vary.
Example:
Fixed Costs = $80,000; CM % = 64%
$$\text{Break-Even Revenue} = \frac{$80,000}{0.64} = $125,000$$


3. Averages and Expectations

Weighted Average

$$\text{Weighted Average} = \frac{\displaystyle\sum_{i}(w_i \times x_i)}{\displaystyle\sum_{i} w_i}$$

Component Definition
Numerator Sum of each value multiplied by its weight
Denominator Sum of all weights
$w_i$ Weight of item $i$ (size, importance, or proportion)
$x_i$ Value of item $i$

Interpretation: An average that accounts for the relative size or importance of each observation — larger weights pull the result closer to their value.
Use case: Calculating a blended interest rate across loans of different sizes; portfolio return.
Example:
A company has two loans: $200K at 5% and $800K at 8%.
$$\text{Weighted Avg Rate} = \frac{(200{,}000 \times 5%) + (800{,}000 \times 8%)}{200{,}000 + 800{,}000} = \frac{10{,}000 + 64{,}000}{1{,}000{,}000} = 7.4%$$


Expected Value (EV)

$$\text{EV} = \sum_{i} p_i \times x_i$$

Component Definition
$p_i$ Probability of outcome $i$ (all probabilities must sum to 1)
$x_i$ Payoff or value of outcome $i$

Interpretation: The probability-weighted average outcome across all scenarios.
Use case: Deciding between business options when outcomes are uncertain.
Example:
A new product launch has three scenarios:

Scenario Probability Profit
Strong market 40% +$500K
Moderate market 45% +$150K
Weak market 15% −$200K

$$\text{EV} = (0.40 \times 500) + (0.45 \times 150) + (0.15 \times -200) = 200 + 67.5 - 30 = $237.5\text{K}$$


4. Demand and Elasticity

% Change

$$% \text{ Change} = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100$$

Component Definition
Numerator New Value − Old Value = the absolute change
Denominator Old Value = the baseline or starting point

Interpretation: Relative change expressed as a percentage of the starting value.
Use case: Calculating revenue growth, price changes, or volume shifts.
Example:
Units sold went from 4,000 to 4,600.
$$% \text{ Change} = \frac{4{,}600 - 4{,}000}{4{,}000} = \frac{600}{4{,}000} = +15%$$


Price Elasticity of Demand (PED)

$$\text{PED} = \frac{% \text{ Change in Quantity Demanded}}{% \text{ Change in Price}}$$

Component Definition
Numerator % change in quantity demanded — how much demand shifted
Denominator % change in price — what caused the demand shift

Interpretation:

  • $|\text{PED}| > 1$ → Elastic — demand is sensitive to price; raising price reduces total revenue
  • $|\text{PED}| < 1$ → Inelastic — demand is insensitive to price; raising price increases total revenue
  • The result is normally negative (price up → demand down)

Use case: Setting prices to maximize revenue; predicting volume impact of price changes.
Example:
Price raised from $10 → $11 (+10%). Demand fell from 1,000 → 850 units (−15%).
$$\text{PED} = \frac{-15%}{+10%} = -1.5 \quad \Rightarrow \text{Elastic — raising price reduces total revenue}$$


5. Time Value of Money

Simple Interest

$$\text{Interest} = P \times r \times t$$

Component Definition
$P$ Principal — the original amount borrowed or invested
$r$ Annual interest rate (as a decimal, e.g., 6% = 0.06)
$t$ Time in years

Interpretation: Interest earned only on the original principal; no compounding.
Use case: Short-term loans, trade credit, or simple savings instruments.
Example:
A $5,000 short-term loan at 6% per year for 9 months ($t = 0.75$).
$$\text{Interest} = $5,000 \times 0.06 \times 0.75 = $225$$


Compound Interest — Future Value

$$\text{FV} = P \times (1 + r)^t$$

Component Definition
$P$ Principal — initial amount
$r$ Annual interest rate (decimal)
$t$ Number of compounding periods (years)

Interpretation: The value your money grows to when interest is earned on both the principal and all previously accumulated interest.
Use case: Projecting investment or savings account balances over time.
Example:
$10,000 invested at 7% per year for 5 years.
$$\text{FV} = $10,000 \times (1.07)^5 = $10,000 \times 1.4026 = $14,026$$


Present Value (PV)

$$\text{PV} = \frac{\text{Future Value}}{(1 + r)^t}$$

Component Definition
Numerator Future Value — the cash amount expected to be received
Denominator $(1 + r)^t$ — discount factor; how much $1 today grows to in $t$ years at rate $r$
$r$ Discount rate (opportunity cost of capital)
$t$ Number of years until the cash is received

Interpretation: What a future cash amount is worth in today's dollars — accounts for the fact that money available now is more valuable than money received later.
Use case: Valuing a future payment; comparing investment options on a like-for-like basis.
Example:
You will receive $14,026 in 5 years. Your discount rate is 7%.
$$\text{PV} = \frac{$14,026}{(1.07)^5} = \frac{$14,026}{1.4026} = $10,000$$


Future Value (FV)

$$\text{FV} = \text{PV} \times (1 + r)^t$$

(Same mechanics as Compound Interest — see above.)
Use case: Planning how much a current savings balance will grow to at a future date.
Example:
You invest $20,000 today at 8% for 10 years.
$$\text{FV} = $20,000 \times (1.08)^{10} = $20,000 \times 2.1589 = $43,178$$


Annuity — Present Value

$$\text{Annuity PV} = \text{PMT} \times \frac{1 - (1 + r)^{-n}}{r}$$

Component Definition
PMT Fixed payment amount per period
Numerator $1 - (1+r)^{-n}$ — total discount factor across all $n$ periods
Denominator $r$ — the periodic discount rate
$n$ Number of periods

Interpretation: The lump-sum value today of a fixed stream of future payments.
Use case: Pricing a loan, valuing a lease, determining how much a pension is worth today.
Example:
A 5-year lease pays $12,000/year. Discount rate = 8%.
$$\text{Annuity PV} = $12,000 \times \frac{1 - (1.08)^{-5}}{0.08} = $12,000 \times \frac{1 - 0.6806}{0.08} = $12,000 \times 3.993 = $47,916$$


Annuity — Future Value

$$\text{Annuity FV} = \text{PMT} \times \frac{(1 + r)^n - 1}{r}$$

Component Definition
PMT Fixed payment amount per period
Numerator $(1+r)^n - 1$ — total compound growth accumulated above the payments
Denominator $r$ — the periodic interest rate
$n$ Number of periods

Interpretation: The total value accumulated at the end of the period if you make equal payments each period and they earn compound interest.
Use case: Calculating the balance of a savings plan or pension fund at maturity.
Example:
You save $500/month for 10 years at 6% annual rate → 0.5%/month, $n = 120$ months.
$$\text{Annuity FV} = $500 \times \frac{(1.005)^{120} - 1}{0.005} = $500 \times \frac{0.8194}{0.005} = $500 \times 163.88 = $81,940$$


6. Investment Returns

Return on Investment (ROI)

$$\text{ROI} = \frac{\text{Final Value} - \text{Initial Investment}}{\text{Initial Investment}} \times 100$$

Component Definition
Numerator Net Gain = final value minus what you originally paid
Denominator Initial Investment = the total upfront capital outlay

Interpretation: The percentage return earned relative to what was invested.
Use case: Quickly comparing two investments or marketing campaigns on a common scale.
Example:
You spend $8,000 on a marketing campaign. It generates $11,200 in attributable revenue.
$$\text{ROI} = \frac{$11,200 - $8,000}{$8,000} = \frac{$3,200}{$8,000} = 40%$$


Compound Annual Growth Rate (CAGR)

$$\text{CAGR} = \left(\frac{\text{Ending Value}}{\text{Beginning Value}}\right)^{\frac{1}{n}} - 1$$

Component Definition
Numerator Ending Value — value at the end of the period
Denominator Beginning Value — value at the start of the period
Exponent $\frac{1}{n}$ Converts total growth into a per-year rate over $n$ years

Interpretation: The constant annual growth rate that would take the beginning value to the ending value over $n$ years — smooths out year-to-year volatility.
Use case: Comparing investments or business metrics (revenue, users) that span different time horizons.
Example:
A company's revenue grew from $2.0M to $3.5M over 4 years.
$$\text{CAGR} = \left(\frac{3.5}{2.0}\right)^{1/4} - 1 = (1.75)^{0.25} - 1 = 1.1501 - 1 = 15.0%$$


Payback Period

$$\text{Payback Period} = \frac{\text{Initial Investment}}{\text{Annual Net Cash Inflow}}$$

Component Definition
Numerator Initial Investment = total upfront capital outlay
Denominator Annual Net Cash Inflow = net cash generated per year from the investment

Interpretation: The number of years required to recover the initial investment through operating cash flows.
Use case: Quick liquidity screening — preferred when capital recovery speed matters more than total return.
Example:
A machine costs $120,000 and generates $30,000 net cash/year.
$$\text{Payback Period} = \frac{$120,000}{$30,000} = 4.0 \text{ years}$$


Net Present Value (NPV)

$$\text{NPV} = \sum_{t=1}^{n} \frac{\text{Cash Flow}_t}{(1 + r)^t} ;-; \text{Initial Investment}$$

Component Definition
Numerator Cash Flow$_t$ = net cash inflow in year $t$
Denominator $(1+r)^t$ — the discount factor for year $t$
$r$ Discount rate (cost of capital / hurdle rate)
Initial Investment Upfront cost at time 0 (subtracted because it is a cash outflow)

Interpretation:

  • NPV > 0 → The project creates value; accept.
  • NPV < 0 → The project destroys value; reject.
  • NPV = 0 → The project exactly meets the required return.

Use case: Capital budgeting — deciding whether a project, acquisition, or expansion is financially worthwhile.
Example:
A $100,000 machine generates $45,000/year for 3 years. Discount rate = 10%.

Year Cash Flow Discount Factor PV of Cash Flow
1 $45,000 ÷ 1.10¹ = 1.100 $40,909
2 $45,000 ÷ 1.10² = 1.210 $37,190
3 $45,000 ÷ 1.10³ = 1.331 $33,809
Sum of PVs $111,908

$$\text{NPV} = $111,908 - $100,000 = +$11,908 \quad \Rightarrow \text{Accept the project}$$


Internal Rate of Return (IRR)

$$\text{IRR is the rate } r \text{ such that:} \quad \sum_{t=1}^{n} \frac{\text{Cash Flow}_t}{(1 + r)^t} - \text{Initial Investment} = 0$$

Interpretation: The annualized return the project generates — the discount rate that makes NPV exactly zero.
Decision rule: Accept if IRR > Hurdle Rate (cost of capital).
Use case: Ranking competing projects; comparing project return against the cost of borrowing.
Example (same project as NPV above):
Initial Investment = $100,000; Cash flows = $45,000/year × 3 years.
Solving iteratively: NPV = 0 at r ≈ 16.7%.
Hurdle rate = 10% → IRR (16.7%) > Hurdle Rate → Accept the project.


7. Cost of Capital

Weighted Average Cost of Capital (WACC)

$$\text{WACC} = \left(\frac{E}{V} \times R_e\right) + \left(\frac{D}{V} \times R_d \times (1 - T)\right)$$

Component Definition
$E$ Market value of equity
$D$ Market value of debt
$V = E + D$ Total firm value
$E/V$ Equity weight — fraction of financing from equity
$D/V$ Debt weight — fraction of financing from debt
$R_e$ Cost of equity (return required by shareholders)
$R_d$ Pre-tax cost of debt (interest rate on borrowing)
$T$ Corporate tax rate (interest is tax-deductible, so after-tax debt cost = $R_d \times (1-T)$)

Interpretation: The blended minimum return the company must earn on its assets to satisfy all investors (both debt and equity holders).
Use case: Discount rate for NPV/DCF valuations; hurdle rate for capital budgeting.
Example:
Capital structure: 70% equity at 12% cost; 30% debt at 6% pre-tax; tax rate = 25%.
$$\text{WACC} = (0.70 \times 12%) + (0.30 \times 6% \times 0.75) = 8.40% + 1.35% = 9.75%$$


CAPM — Cost of Equity

$$R_e = R_f + \beta \times (R_m - R_f)$$

Component Definition
$R_f$ Risk-free rate (e.g., 10-year government bond yield)
$\beta$ Beta — the stock's sensitivity to market movements ($\beta = 1$ moves with the market; $\beta &gt; 1$ is more volatile)
$R_m$ Expected market return (e.g., long-run S&P 500 average ≈ 10%)
$(R_m - R_f)$ Market risk premium — extra return demanded for bearing market risk

Interpretation: The return equity investors require, compensating them for the risk-free rate plus a premium proportional to how volatile the stock is relative to the broader market.
Use case: Estimating cost of equity for WACC; valuing equities in DCF models.
Example:
Risk-free rate = 4%; Expected market return = 10%; Beta = 1.3
$$R_e = 4% + 1.3 \times (10% - 4%) = 4% + 7.8% = 11.8%$$


8. Liquidity and Leverage

Current Ratio

$$\text{Current Ratio} = \frac{\text{Current Assets}}{\text{Current Liabilities}}$$

Component Definition
Numerator Current Assets — cash, receivables, inventory; assets convertible to cash within 12 months
Denominator Current Liabilities — obligations due within 12 months

Interpretation:

  • > 1.0 → Short-term assets exceed short-term obligations (liquid)
  • < 1.0 → Potential liquidity problem

Use case: Lender covenant checks; quick assessment of short-term financial health.
Example:
Current Assets = $850,000 (cash $300K + receivables $250K + inventory $300K); Current Liabilities = $400,000
$$\text{Current Ratio} = \frac{$850,000}{$400,000} = 2.1$$


Quick Ratio (Acid-Test)

$$\text{Quick Ratio} = \frac{\text{Current Assets} - \text{Inventory}}{\text{Current Liabilities}}$$

Component Definition
Numerator Current Assets minus Inventory — excludes the least liquid current asset
Denominator Current Liabilities — obligations due within 12 months

Interpretation: A stricter liquidity test — can the company meet near-term obligations without relying on selling inventory?
Use case: Assessing liquidity in industries where inventory is slow to convert to cash (manufacturing, retail).
Example:
Using same data: Current Assets = $850,000; Inventory = $300,000; Current Liabilities = $400,000
$$\text{Quick Ratio} = \frac{$850,000 - $300,000}{$400,000} = \frac{$550,000}{$400,000} = 1.4$$


Debt-to-Equity Ratio (D/E)

$$\text{D/E} = \frac{\text{Total Debt}}{\text{Total Shareholders' Equity}}$$

Component Definition
Numerator Total Debt = all interest-bearing liabilities (short-term + long-term)
Denominator Total Shareholders' Equity = total assets minus total liabilities

Interpretation: How many dollars of debt exist for every dollar of equity. Higher = more financial leverage and risk.
Use case: Credit analysis; evaluating capital structure risk; comparing leverage across peers.
Example:
Total Debt = $1,200,000 (bank loans + bonds); Equity = $800,000
$$\text{D/E} = \frac{$1,200,000}{$800,000} = 1.5$$ There is $1.50 of debt for every $1 of equity.


Interest Coverage Ratio

$$\text{Interest Coverage} = \frac{\text{EBIT}}{\text{Interest Expense}}$$

Component Definition
Numerator EBIT = Earnings Before Interest and Taxes (operating profit)
Denominator Interest Expense = annual interest owed on all outstanding debt

Interpretation: How many times over the company can pay its interest bill from operating profit.

  • > 3× is generally considered safe
  • < 1.5× is a warning sign

Use case: Bond analysis; credit risk assessment; covenant monitoring.
Example:
EBIT = $500,000; Annual interest expense = $80,000
$$\text{Interest Coverage} = \frac{$500,000}{$80,000} = 6.25\times \quad \Rightarrow \text{Operating profit covers interest 6.25 times}$$


9. Unit Economics

Customer Lifetime Value (CLV)

$$\text{CLV} = \text{Avg. Revenue per Period} \times \text{Gross Margin %} \times \text{Avg. Customer Lifetime (periods)}$$

Component Definition
Avg. Revenue per Period Average monthly (or annual) revenue from one customer
Gross Margin % Fraction of revenue remaining after variable delivery costs
Avg. Customer Lifetime Expected number of periods before the customer churns

Interpretation: The total gross profit a typical customer generates over their entire relationship with the company.
Use case: Setting maximum allowable customer acquisition cost (CAC); justifying retention spend.
Example:
A subscription app earns $15/month per user; gross margin = 75%; average customer stays 28 months.
$$\text{CLV} = $15 \times 75% \times 28 = $315$$


CAC Payback Period

$$\text{CAC Payback} = \frac{\text{Customer Acquisition Cost (CAC)}}{\text{Gross Profit per Period per Customer}}$$

Component Definition
Numerator CAC = total sales & marketing spend ÷ number of new customers acquired
Denominator Gross Profit per Period = Revenue per customer × Gross Margin %

Interpretation: How many periods it takes to recover the cost of acquiring one customer from the gross profit that customer generates.
Use case: Assessing growth efficiency; ensuring acquisition cost is justified by lifetime value.
Example:
CAC = $180; Monthly gross profit per customer = $15 × 75% = $11.25
$$\text{CAC Payback} = \frac{$180}{$11.25} = 16 \text{ months}$$ Sanity check: CLV ($315) >> CAC ($180) → healthy unit economics.


10. Depreciation

Straight-Line Depreciation (Annual)

$$\text{Annual Depreciation} = \frac{\text{Cost} - \text{Salvage Value}}{\text{Useful Life (years)}}$$

Component Definition
Numerator Cost − Salvage Value = the total amount to be depreciated (the "depreciable base")
Denominator Useful Life = how many years the asset is expected to be used
Salvage Value Estimated resale or scrap value at the end of the asset's useful life

Interpretation: Allocates the depreciable cost evenly across each year of the asset's useful life.
Use case: Forecasting D&A expense on the income statement; calculating EBITDA.
Example:
A delivery van costs $48,000, has a salvage value of $6,000, and a useful life of 6 years.
$$\text{Annual Depreciation} = \frac{$48,000 - $6,000}{6} = \frac{$42,000}{6} = $7,000/\text{year}$$


Book Value (Net of Depreciation)

$$\text{Book Value} = \text{Original Cost} - \text{Accumulated Depreciation}$$

Component Definition
Original Cost Purchase price of the asset
Accumulated Depreciation Total depreciation charged since purchase = Annual Depreciation × years elapsed

Interpretation: The remaining accounting value of the asset carried on the balance sheet.
Use case: Balance sheet reporting; calculating gain or loss on asset disposal.
Example:
After 3 years: Accumulated Depreciation = $7,000 × 3 = $21,000
$$\text{Book Value} = $48,000 - $21,000 = $27,000$$


11. DuPont Analysis

Return on Equity (ROE) — DuPont Decomposition

$$\text{ROE} = \underbrace{\frac{\text{Net Profit}}{\text{Revenue}}}_{\text{Net Margin}} ;\times; \underbrace{\frac{\text{Revenue}}{\text{Avg. Total Assets}}}_{\text{Asset Turnover}} ;\times; \underbrace{\frac{\text{Avg. Total Assets}}{\text{Avg. Shareholders' Equity}}}_{\text{Equity Multiplier}}$$

Driver What it measures How to improve
Net Margin Profitability — profit kept per sales dollar Cut costs or raise prices
Asset Turnover Efficiency — sales generated per dollar of assets Increase revenue or reduce assets
Equity Multiplier Leverage — assets funded per dollar of equity Take on more debt (increases risk)

Interpretation: Decomposes ROE into three levers so management can diagnose why ROE is high or low.
Use case: Identifying whether ROE improvements come from better margins, better asset use, or higher leverage.
Example:
Net Margin = 8%; Asset Turnover = 1.6×; Equity Multiplier = 2.5×
$$\text{ROE} = 8% \times 1.6 \times 2.5 = 32%$$ The high ROE is partly driven by leverage (2.5×); reducing leverage to 1.5× would drop ROE to 19.2%.


Asset Turnover

$$\text{Asset Turnover} = \frac{\text{Revenue}}{\text{Average Total Assets}}$$

Component Definition
Numerator Revenue = total annual sales
Denominator Average Total Assets = (Opening assets + Closing assets) ÷ 2

Interpretation: How many dollars of revenue are generated for every dollar of assets held.
Example:
Revenue = $4.8M; Beginning assets = $2.8M; Ending assets = $3.2M → Average = $3.0M
$$\text{Asset Turnover} = \frac{$4.8M}{$3.0M} = 1.6\times$$


Equity Multiplier

$$\text{Equity Multiplier} = \frac{\text{Average Total Assets}}{\text{Average Shareholders' Equity}}$$

Component Definition
Numerator Average Total Assets = total assets the business controls
Denominator Average Shareholders' Equity = net assets funded by owners

Interpretation: How many dollars of assets exist per dollar of equity — measures balance-sheet leverage.
Example:
Avg Total Assets = $3.0M; Avg Equity = $1.2M
$$\text{Equity Multiplier} = \frac{$3.0M}{$1.2M} = 2.5\times$$


12. Efficiency and Working Capital

Inventory Turnover

$$\text{Inventory Turnover} = \frac{\text{Cost of Goods Sold (COGS)}}{\text{Average Inventory}}$$

Component Definition
Numerator COGS = cost of inventory actually sold during the period
Denominator Average Inventory = (Opening inventory + Closing inventory) ÷ 2

Interpretation: How many times inventory is fully sold and replaced during the year. Higher = leaner operations.
Use case: Identifying slow-moving stock; comparing supply chain efficiency with peers.
Example:
Annual COGS = $1,800,000; Beginning inventory = $300,000; Ending inventory = $420,000 → Average = $360,000
$$\text{Inventory Turnover} = \frac{$1,800,000}{$360,000} = 5.0\times$$


Days Inventory Outstanding (DIO)

$$\text{DIO} = \frac{365}{\text{Inventory Turnover}}$$

Component Definition
Numerator 365 — days in a year
Denominator Inventory Turnover — how many full cycles occur per year

Interpretation: The average number of days inventory sits on the shelf before being sold.
Use case: Working capital optimization; identifying excess or obsolete stock.
Example:
$$\text{DIO} = \frac{365}{5.0} = 73 \text{ days}$$


Days Sales Outstanding (DSO)

$$\text{DSO} = \frac{\text{Accounts Receivable}}{\text{Annual Revenue}} \times 365$$

Component Definition
Numerator Accounts Receivable = money owed by customers at period end
Denominator Annual Revenue ÷ 365 = average daily revenue (dividing AR by this gives days outstanding)

Interpretation: The average number of days it takes to collect cash after making a sale.
Use case: Managing credit policy; identifying collection problems; cash flow forecasting.
Example:
Accounts Receivable = $180,000; Annual Revenue = $1,800,000
$$\text{DSO} = \frac{$180,000}{$1,800,000} \times 365 = 0.10 \times 365 = 36.5 \text{ days}$$


Days Payable Outstanding (DPO)

$$\text{DPO} = \frac{\text{Accounts Payable}}{\text{COGS}} \times 365$$

Component Definition
Numerator Accounts Payable = money owed to suppliers at period end
Denominator COGS ÷ 365 = average daily purchases from suppliers

Interpretation: The average number of days the company takes to pay its suppliers. Higher DPO = company holds cash longer (favorable for liquidity).
Use case: Supplier negotiation; cash management strategy.
Example:
Accounts Payable = $180,000; Annual COGS = $1,800,000
$$\text{DPO} = \frac{$180,000}{$1,800,000} \times 365 = 36.5 \text{ days}$$


Cash Conversion Cycle (CCC)

$$\text{CCC} = \text{DIO} + \text{DSO} - \text{DPO}$$

Component Definition
DIO Days inventory is held before being sold
DSO Days to collect cash from customers after the sale
DPO Days taken to pay suppliers — subtracted because it delays the cash outflow

Interpretation: The number of days cash is tied up in operations from the moment you pay for inventory to the moment you collect from customers. Lower CCC = better cash efficiency.
Use case: Working capital management; identifying cash flow bottlenecks.
Example:
DIO = 73 days; DSO = 36.5 days; DPO = 36.5 days
$$\text{CCC} = 73 + 36.5 - 36.5 = 73 \text{ days}$$ To improve: negotiate supplier terms to extend DPO to 50 days → CCC drops to 59.5 days.


13. Multi-Product Break-Even

Weighted Contribution Margin

$$\text{Weighted CM} = \sum_{i}\left(\text{Product Mix %}_i \times \text{CM per Unit}_i\right)$$

Component Definition
Product Mix % Share of total unit sales each product represents (all must sum to 100%)
CM per Unit Contribution margin of each individual product

Interpretation: The average contribution per unit sold across the entire product portfolio, weighted by sales mix.
Use case: Break-even analysis when a company sells more than one product.
Example:
Product A: 60% of sales, CM = $20/unit. Product B: 40% of sales, CM = $8/unit.
$$\text{Weighted CM} = (0.60 \times $20) + (0.40 \times $8) = $12.00 + $3.20 = $15.20$$


Break-Even Units (Multi-Product)

$$\text{Break-Even Units (total)} = \frac{\text{Total Fixed Costs}}{\text{Weighted CM per Unit}}$$

Component Definition
Numerator Total Fixed Costs = overhead that must be covered
Denominator Weighted CM per Unit = blended average contribution across the product mix

Use case: Planning total output required across a product portfolio to reach break-even.
Example:
Fixed Costs = $76,000; Weighted CM = $15.20
$$\text{Break-Even Units (total)} = \frac{$76,000}{$15.20} = 5,000 \text{ units}$$ Split by mix: 5,000 × 60% = 3,000 units of A; 5,000 × 40% = 2,000 units of B.


14. Bonds and Valuation

Bond Price

$$\text{Bond Price} = \sum_{t=1}^{n} \frac{\text{Coupon Payment}}{(1 + r)^t} + \frac{\text{Face Value}}{(1 + r)^n}$$

Component Definition
Coupon Payment Fixed periodic cash interest = Face Value × Coupon Rate
Face Value Par value of the bond, repaid in full at maturity (typically $1,000)
Numerator (coupons) The cash interest received each period
Numerator (final term) The face value received at maturity
Denominator $(1 + r)^t$ — discount factor for each period using market yield $r$
$n$ Total number of periods until maturity

Interpretation: A bond's price equals the present value of all future cash flows discounted at the market yield.

  • Market yield rises → Bond price falls (inverse relationship)
  • Market yield falls → Bond price rises

Use case: Valuing bonds; understanding the price-yield relationship.
Example:
3-year bond; Face = $1,000; Coupon = 5% ($50/year); Market yield = 7%

Year Cash Flow Discount Factor PV of Cash Flow
1 $50 ÷ 1.07¹ = 1.070 $46.73
2 $50 ÷ 1.07² = 1.145 $43.67
3 $1,050 ÷ 1.07³ = 1.225 $857.96

$$\text{Bond Price} = $46.73 + $43.67 + $857.96 = $948.36$$ The bond trades below par ($1,000) because its coupon rate (5%) < market yield (7%).


Dividend Discount Model — Gordon Growth Model

$$P_0 = \frac{D_1}{r - g}$$

Component Definition
Numerator $D_1$ Next year's expected dividend per share = $D_0 \times (1 + g)$
Denominator $(r - g)$ Required return minus the perpetual dividend growth rate
$r$ Investor's required rate of return (cost of equity)
$g$ Constant annual growth rate of dividends (must be $&lt; r$)

Interpretation: The fair value of a stock equals the present value of its dividends growing at a constant rate forever.
Use case: Valuing mature, dividend-paying companies with stable growth (utilities, blue-chip stocks).
Example:
Last dividend paid $D_0 = $2.00$; dividends grow at 4%/year; required return = 9%.
$$D_1 = $2.00 \times 1.04 = $2.08$$ $$P_0 = \frac{$2.08}{9% - 4%} = \frac{$2.08}{0.05} = $41.60$$


15. Variance and Sensitivity Analysis

Absolute Variance

$$\text{Variance} = \text{Actual} - \text{Budget}$$

Sign Revenue line Cost line
Positive Favorable — actual > budget Unfavorable — actual > budget
Negative Unfavorable — actual < budget Favorable — actual < budget

Use case: Monthly management reporting; identifying over- and under-performing areas.
Example:
Budgeted revenue: $500,000; Actual revenue: $470,000
$$\text{Revenue Variance} = $470,000 - $500,000 = -$30,000 \quad \text{(Unfavorable)}$$


Variance %

$$\text{Variance %} = \frac{\text{Actual} - \text{Budget}}{\text{Budget}} \times 100$$

Component Definition
Numerator Absolute Variance = Actual minus Budget
Denominator Budget = the planned or reference amount

Interpretation: Expresses the variance as a percentage of the plan — useful for scaling comparisons across line items of very different sizes.
Example:
$$\text{Variance %} = \frac{$470,000 - $500,000}{$500,000} = \frac{-$30,000}{$500,000} = -6.0%$$


Profit Sensitivity to Volume

$$\Delta\text{Profit} = \text{Contribution Margin per Unit} \times \Delta\text{Volume}$$

Component Definition
CM per Unit Profit added (or lost) for each additional (or fewer) unit sold
ΔVolume Increase or decrease in units sold

Interpretation: Fixed costs do not change with volume, so every unit above break-even adds exactly CM per unit to profit — and every unit below subtracts it.
Use case: Scenario analysis ("what if sales drop 10%?"); quantifying downside risk quickly.
Example:
CM per Unit = $16; A supply disruption cuts volume by 800 units.
$$\Delta\text{Profit} = $16 \times (-800) = -$12,800$$ The profit impact is an immediate $12,800 decline with no offset from fixed cost savings.


All examples within each section use consistent numbers so the formulas can be traced and cross-referenced easily.


16. Capacity and Operations

Capacity Utilization Rate

$$\text{Capacity Utilization} = \frac{\text{Actual Output}}{\text{Maximum Possible Output}} \times 100$$

Component Definition
Numerator Actual Output = units (or hours) actually produced in the period
Denominator Maximum Possible Output = theoretical maximum at full capacity

Interpretation: What percentage of total available capacity is being used.

  • < 70% → Significant idle capacity; fixed costs are spread over fewer units, raising unit cost
  • 70–85% → Typical efficient operating range
  • > 90% → Risk of bottlenecks, quality issues, and inability to handle demand spikes

Use case: Identifying whether a capacity investment is needed; diagnosing high unit costs in a manufacturing case.
Example:
A factory can produce 20,000 units/month at full capacity. It currently produces 14,000.
$$\text{Capacity Utilization} = \frac{14,000}{20,000} = 70%$$ The plant has 6,000 units/month of idle capacity — before building a new facility, management should ask why utilization is low (demand shortfall? supply constraint? scheduling?).


Cost per Unit at Different Utilization Levels

$$\text{Unit Cost} = \frac{\text{Fixed Costs}}{\text{Actual Output}} + \text{Variable Cost per Unit}$$

Component Definition
Numerator Fixed Costs = costs unchanged regardless of output (rent, depreciation, salaried staff)
Denominator Actual Output = units actually produced
Variable Cost per Unit Costs that scale directly with output (materials, direct labor)

Interpretation: As output rises, fixed costs are spread over more units, so unit cost falls — this is operating leverage. Conversely, underutilization inflates unit cost.
Use case: Explaining why a plant running at 50% utilization has uncompetitively high unit costs; pricing decisions.
Example:
Fixed Costs = $200,000/month; Variable Cost = $8/unit.

Utilization Units Produced Fixed Cost per Unit Variable Cost Unit Cost
50% 10,000 $20.00 $8.00 $28.00
70% 14,000 $14.29 $8.00 $22.29
100% 20,000 $10.00 $8.00 $18.00

Running at 70% vs 100% costs an extra $4.29 per unit — purely due to underutilization.


Bottleneck Throughput

$$\text{System Throughput} = \text{Bottleneck Capacity (units per period)}$$

$$\text{Bottleneck Utilization} = \frac{\text{Demand Rate}}{\text{Bottleneck Capacity}} \times 100$$

Component Definition
Bottleneck The single process step with the lowest capacity — it limits the entire system
Demand Rate Volume of orders or jobs arriving per period

Interpretation: The output of an entire operation is capped by its slowest step. No amount of improvement elsewhere increases total throughput unless the bottleneck is addressed.
Use case: Operations cases involving queues, factory floor redesign, or service capacity.
Example:
A 3-step assembly line: Step A = 500 units/hr; Step B = 320 units/hr; Step C = 450 units/hr.
Bottleneck = Step B (320 units/hr) → System output is capped at 320 units/hr regardless of Steps A and C.
If demand = 400 units/hr:
$$\text{Bottleneck Utilization} = \frac{400}{320} = 125% \quad \Rightarrow \text{Backlog builds — Step B must be expanded}$$


17. Market Analysis

Market Share (Value)

$$\text{Market Share %} = \frac{\text{Company Revenue}}{\text{Total Market Revenue}} \times 100$$

Component Definition
Numerator Company Revenue = the firm's sales in a defined market and period
Denominator Total Market Revenue = all sales by all competitors in that same market

Interpretation: The fraction of total market spending captured by the company.
Use case: Competitive benchmarking; tracking whether growth is coming from market expansion or share gains.
Example:
The company earns $48M; total market = $320M.
$$\text{Market Share} = \frac{$48M}{$320M} = 15%$$


Market Share (Volume)

$$\text{Market Share % (volume)} = \frac{\text{Company Units Sold}}{\text{Total Market Units Sold}} \times 100$$

Interpretation: Share based on units rather than dollars. Comparing value share vs volume share reveals whether the company sells at a premium (value share > volume share) or a discount (volume share > value share).
Example:
Company sells 90,000 units; total market = 750,000 units.
$$\text{Volume Share} = \frac{90,000}{750,000} = 12%$$ Value share = 15%; Volume share = 12% → The company commands a price premium (it captures more revenue per unit than the average competitor).


Relative Market Share

$$\text{Relative Market Share} = \frac{\text{Company Market Share}}{\text{Largest Competitor's Market Share}}$$

Component Definition
Numerator The company's own market share
Denominator The market share of the single largest competitor

Interpretation: A ratio > 1.0 means the company is the market leader. Used in BCG matrix analysis: a relative share > 1× confers scale advantages in cost and brand.
Use case: Competitive position assessment; portfolio strategy (Stars, Cash Cows, etc.).
Example:
Company share = 15%; Largest competitor = 25%.
$$\text{Relative Market Share} = \frac{15%}{25%} = 0.6\times \quad \Rightarrow \text{The company is not the market leader}$$


Market Growth Rate

$$\text{Market Growth Rate} = \frac{\text{Current Year Market Size} - \text{Prior Year Market Size}}{\text{Prior Year Market Size}} \times 100$$

Component Definition
Numerator Absolute growth in total market size (revenue or units) year-over-year
Denominator Prior year market size = the baseline

Interpretation: How fast the overall market is expanding or contracting — distinct from the company's own revenue growth.
Use case: Distinguishing organic growth from share gains; market attractiveness screening.
Example:
Market was $300M last year; it is $324M this year.
$$\text{Market Growth} = \frac{$324M - $300M}{$300M} = 8%$$ If the company's revenue grew 15%, it outpaced the market by 7pp → it gained share.


Total Addressable Market (TAM) — Bottom-Up Sizing

$$\text{TAM} = \text{Number of Potential Customers} \times \text{Average Annual Spend per Customer}$$

Component Definition
Number of Potential Customers Everyone who could plausibly buy the product (segment the population if needed)
Avg. Annual Spend per Customer Average dollars spent on this category per year

Interpretation: The maximum revenue opportunity if the company captured 100% of the market.
Use case: Market entry decisions; investor pitch sizing; setting growth ambition.
Example:
Target segment: 4 million small businesses in the country. Each spends ~$600/year on the software category.
$$\text{TAM} = 4{,}000{,}000 \times $600 = $2.4\text{ billion}$$


18. Pricing and Revenue Decomposition

Revenue Decomposition

$$\text{Revenue} = \underbrace{\text{Price}}_{\text{rate}} \times \underbrace{\text{Volume}}_{\text{quantity}}$$

$$\Delta\text{Revenue} = \underbrace{(\Delta\text{Price} \times Q_{\text{old}})}_{\text{Price effect}} + \underbrace{(\Delta Q \times P_{\text{new}})}_{\text{Volume effect}}$$

Component Definition
Price effect Revenue change caused solely by the price change, holding volume constant
Volume effect Revenue change caused by the volume change at the new price

Interpretation: Any revenue movement can be split into what was driven by pricing versus what was driven by volume. This is the first diagnostic in any profitability case.
Use case: Diagnosing a revenue decline — is it a pricing problem, a volume problem, or both?
Example:
Last year: 10,000 units at $30 = $300,000. This year: 8,500 units at $32 = $272,000 (−$28,000).

Effect Calculation Amount
Price effect +$2 × 10,000 units +$20,000
Volume effect −1,500 units × $32 −$48,000
Net change −$28,000

The price increase added $20K but volume loss cost $48K — the net effect is negative, so the price increase was not worth it.


Revenue Growth Decomposition (3 drivers)

$$\text{Revenue Growth} = \underbrace{\text{Price Growth}}_{\text{(rate)}} + \underbrace{\text{Volume Growth}}_{\text{(units)}} + \underbrace{\text{Mix Shift}}_{\text{(product mix)}}$$

Driver Definition
Price Growth Change in average selling price, holding mix and volume constant
Volume Growth Change in total units sold, holding price and mix constant
Mix Shift Revenue change from selling proportionally more high-price vs low-price products

Interpretation: Revenue growth comes from three levers simultaneously; isolating each reveals which lever is driving (or dragging) performance.
Use case: Explaining to an interviewer why revenue grew despite a price cut, or why it fell despite volume gains.
Example:
Revenue grew 6%. Breakdown: Average price −2% (competitive pressure); Volume +5%; Mix +3% (shift toward premium SKUs).
The company is growing despite price erosion — it compensates through volume and premiumization.


Price-Volume Tradeoff: Break-Even Volume Change

$$\Delta Q_{\text{break-even}} = \frac{-\Delta P}{\text{CM per Unit} + \Delta P}$$

Component Definition
Numerator $-\Delta P$ = the revenue lost per existing unit due to the price reduction
Denominator CM per Unit + ΔP = the new contribution per unit after the price change

Interpretation: If you cut the price by $\Delta P$, how many additional units must you sell to keep total profit unchanged?
Use case: Deciding whether a price cut or promotional discount is financially justified.
Example:
Current price = $25; Variable cost = $9; CM = $16. Considering a $3 price cut → new price $22, new CM = $13.
$$\Delta Q_{\text{break-even}} = \frac{-(-$3)}{$16 + (-$3)} = \frac{$3}{$13} = 23.1%$$

You must sell at least 23.1% more units just to break even on profit. If PED = −1.5 and the price cut is −12%, expected volume gain ≈ +18% — which falls short of 23.1%, so the price cut destroys profit.


Optimal Price (Maximizing Revenue)

$$\text{Revenue-Maximizing Price} \Rightarrow \text{achieved when } |\text{PED}| = 1$$

For a linear demand curve $Q = a - bP$: $$P^* = \frac{a}{2b}$$

Interpretation: Revenue is maximized at the price point where elasticity = −1 (unit elastic). Above this price, the % volume loss exceeds the % price gain; below it, the opposite is true.
Use case: Setting an initial price for a new product; quick-check in pricing strategy cases.


19. Marketing and Promotions

Marketing ROI (MROI)

$$\text{MROI} = \frac{\text{Incremental Gross Profit from Campaign} - \text{Marketing Spend}}{\text{Marketing Spend}} \times 100$$

Component Definition
Numerator Net incremental profit = gross profit attributable to the campaign minus what was spent
Denominator Marketing Spend = total campaign cost

Interpretation: The profit return generated for every dollar spent on marketing. Unlike simple revenue ROI, this uses gross profit because the cost of goods must be subtracted first.
Use case: Evaluating whether a campaign, channel, or promotion should be continued or scaled.
Example:
A digital campaign costs $50,000 and drives 2,000 incremental units sold. Price = $25; Variable cost = $9 → Gross profit/unit = $16.
$$\text{Incremental Gross Profit} = 2,000 \times $16 = $32,000$$ $$\text{MROI} = \frac{$32,000 - $50,000}{$50,000} = -36% \quad \Rightarrow \text{Campaign loses money — redesign or cut}$$


Return on Ad Spend (ROAS)

$$\text{ROAS} = \frac{\text{Revenue Attributable to Ad Spend}}{\text{Ad Spend}}$$

Component Definition
Numerator Revenue (not profit) directly driven by the advertising
Denominator Total advertising spend in the same period

Interpretation: How many dollars of revenue are generated per dollar of advertising. Note: ROAS uses revenue, not profit — a high ROAS can still be unprofitable if margins are thin.
Use case: Comparing efficiency across ad channels (search, social, display).
Example:
Ad spend = $50,000; Attributed revenue = $200,000.
$$\text{ROAS} = \frac{$200,000}{$50,000} = 4.0\times$$

Every $1 of ad spend returns $4 in revenue. But if gross margin is only 20%, gross profit = $40,000 < ad spend ($50,000) → still unprofitable.


Promotional Lift

$$\text{Promotional Lift %} = \frac{\text{Sales during Promotion} - \text{Baseline Sales}}{\text{Baseline Sales}} \times 100$$

Component Definition
Numerator Incremental sales = actual sales minus what would have been sold without the promotion
Denominator Baseline Sales = expected sales in the same period absent any promotion

Interpretation: How much extra volume (%) the promotion generated above the normal run-rate.
Use case: Measuring whether a promotion actually drove incremental demand or simply pulled forward future purchases.
Example:
Baseline weekly sales = 5,000 units. During the promotion = 6,800 units.
$$\text{Lift} = \frac{6,800 - 5,000}{5,000} = 36%$$


Break-Even Sales Lift for a Promotion

$$\text{Required Lift %} = \frac{-\Delta\text{CM per Unit}}{\text{New CM per Unit}} \times 100$$

Component Definition
Numerator $-\Delta\text{CM}$ = reduction in contribution margin per unit caused by the discount
Denominator New CM per Unit = contribution margin after the discount is applied

Interpretation: The minimum percentage volume increase the promotion must generate for total profit to remain unchanged.
Use case: Deciding whether to run a price promotion; evaluating trade deal terms from a retailer.
Example:
Normal price $25; Variable cost $9; CM = $16. Promotion offers $4 off → new price $21; new CM = $12.
$$\text{Required Lift} = \frac{$4}{$12} = 33.3%$$

The promotion must drive at least 33.3% more volume to break even on profit. Pair this with your PED estimate to judge feasibility.


20. Competitive Analysis

Herfindahl-Hirschman Index (HHI) — Market Concentration

$$\text{HHI} = \sum_{i=1}^{n} s_i^2$$

Component Definition
$s_i$ Market share of firm $i$ expressed as a whole number (e.g., 30 for 30%)
$n$ Number of firms in the market

Interpretation:

  • HHI < 1,500 → Competitive (unconcentrated) market
  • 1,500–2,500 → Moderately concentrated
  • > 2,500 → Highly concentrated / near-monopoly

Use case: Assessing competitive intensity in an industry case; understanding M&A regulatory risk.
Example:
Four firms with shares of 40%, 30%, 20%, 10%:
$$\text{HHI} = 40^2 + 30^2 + 20^2 + 10^2 = 1,600 + 900 + 400 + 100 = 3,000$$ HHI = 3,000 → Highly concentrated market. A merger between the top two firms would face significant antitrust scrutiny.


Price Premium vs. Competitor

$$\text{Price Premium %} = \frac{\text{Company Price} - \text{Competitor Price}}{\text{Competitor Price}} \times 100$$

Component Definition
Numerator The absolute price difference between the company and the reference competitor
Denominator Competitor Price = the benchmark (usually the market average or the largest rival)

Interpretation: How much more (or less) the company charges relative to the competition. A positive premium is only sustainable if backed by differentiation customers value.
Use case: Pricing strategy; diagnosing volume share loss; brand positioning analysis.
Example:
Company price = $32; main competitor = $27.
$$\text{Price Premium} = \frac{$32 - $27}{$27} = 18.5%$$ If volume share is declining, ask: has the premium grown (price-driven loss) or has perceived differentiation eroded (brand-driven loss)?


Competitive Response: Profit Impact of a Competitor Price Cut

$$\Delta\text{Profit (if we do not respond)} = -\Delta Q_{\text{lost}} \times \text{CM per Unit}$$

$$\Delta\text{Profit (if we match the cut)} = (\text{Q}_{\text{retained}} \times \Delta\text{CM}) + (\text{incremental Q won back} \times \text{new CM})$$

Interpretation: When a competitor cuts price, you face two options — do nothing (lose volume) or match (keep volume but at lower margin). Quantifying both is the first step in a competitive response analysis.
Use case: Competitive dynamics cases; deciding whether to start or join a price war.
Example:
A competitor cuts price by $3. You estimate you'll lose 1,200 units/month if you don't respond.
Current CM = $16/unit.
$$\text{Profit impact of doing nothing} = -1,200 \times $16 = -$19,200/\text{month}$$ If matching the cut reduces CM from $16 to $13 but retains all 8,000 units:
$$\text{Profit impact of matching} = 8,000 \times ($13 - $16) = -$24,000/\text{month}$$ In this case, not responding is less costly — unless the volume loss compounds over time.


21. Operating Leverage and Cost Structure

Operating Leverage

$$\text{Operating Leverage} = \frac{\text{Contribution Margin}}{\text{Operating Profit (EBIT)}}$$

Component Definition
Numerator Contribution Margin = Revenue − Total Variable Costs
Denominator Operating Profit (EBIT) = Contribution Margin − Fixed Costs

Interpretation: How many times larger the contribution margin is relative to operating profit — tells you how sensitive profit is to a change in revenue. $$% \Delta\text{Operating Profit} \approx \text{Operating Leverage} \times % \Delta\text{Revenue}$$ A high fixed-cost business (e.g., airlines, software) has high operating leverage: small revenue swings cause large profit swings.
Use case: Assessing profit sensitivity in scenario analysis; explaining why a business is risky in a downturn.
Example:
Revenue = $96,000; Variable costs = $32,000; Fixed costs = $52,000.
CM = $64,000; EBIT = $12,000.
$$\text{Operating Leverage} = \frac{$64,000}{$12,000} = 5.3\times$$ If revenue falls 10%:
$$% \Delta\text{EBIT} \approx 5.3 \times (-10%) = -53%$$ A 10% revenue drop wipes out more than half of operating profit.


Fixed vs. Variable Cost Ratio

$$\text{Fixed Cost Ratio} = \frac{\text{Total Fixed Costs}}{\text{Total Costs}} \times 100$$

Component Definition
Numerator Fixed Costs = costs that do not change with output level
Denominator Total Costs = Fixed Costs + Total Variable Costs

Interpretation: Businesses with a high fixed cost ratio have high operating leverage — profitable when running near capacity, but vulnerable in downturns. Businesses with a high variable cost ratio are more resilient but have lower upside.
Use case: Quickly characterizing a business model's risk profile in an industry case.
Example:
Fixed costs = $200,000; Variable costs at current volume = $80,000; Total costs = $280,000.
$$\text{Fixed Cost Ratio} = \frac{$200,000}{$280,000} = 71.4%$$ This is a high fixed-cost business (e.g., manufacturing, hospitality) — profits are highly sensitive to volume changes.


Profit Impact of a Cost Change

$$\Delta\text{Profit} = -\Delta\text{Cost per Unit} \times \text{Volume}$$

Component Definition
ΔCost per Unit Change in variable cost per unit (positive = cost increase, negative = saving)
Volume Current units sold

Interpretation: A variable cost saving flows directly to profit (dollar for dollar) across all units sold. Fixed cost changes flow to profit in full regardless of volume.
Use case: Quantifying the profit impact of a supplier price increase, wage change, or efficiency improvement.
Example:
A $1.50/unit increase in raw material costs; current volume = 80,000 units/year.
$$\Delta\text{Profit} = -$1.50 \times 80,000 = -$120,000/\text{year}$$

To offset this, the company must either raise prices, cut other costs, or grow volume.


Sections 16–21 cover the quantitative tools most commonly tested in case interviews beyond standard financial statements.