Unit 2: Volatility and risk measurement
Financial Analytics notes · PTU syllabus (MBA 965-26)
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Unit summary
Risk is the heart of finance, and volatility is its most common measure. This unit covers ARCH and GARCH volatility models, volatility clustering, statistical distributions and Value at Risk estimation, hypothesis testing in finance, and Monte Carlo simulation for risk analysis and option pricing.
After this unit you can
- Model volatility with ARCH and GARCH
- Estimate Value at Risk
- Apply hypothesis tests to financial questions
- Use Monte Carlo simulation for risk and option pricing
PTU syllabus topics
- ARCH/GARCH volatility models
- volatility clustering
- statistical distributions and Value at Risk estimation
- hypothesis testing in finance
- Monte Carlo simulation for risk analysis and option pricing
Parametric VaR
Z × σ × portfolio value
Historical VaR
Loss at the chosen percentile of past returns
GARCH(1,1)
σ²ₜ = ω + α ε²ₜ₋₁ + β σ²ₜ₋₁
Monte Carlo
Simulate many paths, read off the loss distribution
Topic 1
ARCH and GARCH models and volatility clustering
- Volatility clustering: large changes tend to follow large changes (financial markets).
- ARCH (Engle, 1982): variance today depends on past squared errors.
- GARCH(1,1) (Bollerslev, 1986): σt² = ω + α e²t−1 + β σ²t−1 — variance depends on past shocks and past variance; α + β close to 1 means persistent volatility.
- Uses: forecasting volatility for risk management, option pricing, Value at Risk.
Example
After a market crash, a GARCH model forecasts higher volatility for the following days, which then decays gradually towards its long-run average.
Topic 2
Statistical distributions in finance
- Normal distribution is a convenient approximation but underestimates extreme losses; Student's t and other fat-tailed distributions fit returns better; lognormal for prices.
Topic 3
Value at Risk
VaR: the maximum loss over a given horizon at a given confidence level under normal market conditions.
Parametric (variance–covariance)
VaR = z × σ × portfolio value × √(days)
Historical simulation
Loss at the chosen percentile of past returns
Monte Carlo
Loss at the percentile of simulated returns
Expected shortfall (CVaR)
Average loss beyond the VaR
Example
Portfolio ₹10 crore, daily σ = 1.5%, 99% confidence (z = 2.33): one-day VaR = 2.33 × 1.5% × 10 crore ≈ ₹35 lakh; ten-day VaR ≈ 35 × √10 ≈ ₹1.1 crore.
- Limitations: says nothing about losses beyond the threshold; depends on assumptions; expected shortfall is now preferred by Basel (FRTB).
- Backtesting: compare actual losses with VaR — too many exceptions mean the model underestimates risk.
Topic 4
Hypothesis testing in finance
- Questions: Is the mean return different from zero? Does a fund beat its benchmark (alpha)? Are returns normally distributed (Jarque–Bera)? Did an event affect prices (event study abnormal returns)? Do two strategies differ?
- Tests: t-tests, F-tests, chi-square, Jarque–Bera, ADF; care with multiple testing and data snooping.
Topic 5
Monte Carlo simulation
- 1Define the model
Price process — geometric Brownian motion
- 2Specify inputs and distributions
Drift, volatility, correlations
- 3Generate many random paths
- 4Compute the outcome for each path
Portfolio value, option payoff
- 5Analyse the distribution
Mean, percentiles, probability of loss
Price path
S(t+Δt) = S(t) × exp[(r − σ² ÷ 2)Δt + σ √Δt × Z]
Option value
Average discounted payoff = e^(−rT) × mean[max(S_T − K, 0)]
- Uses: VaR for complex portfolios, path-dependent options, retirement planning, project risk; accuracy improves with more simulations.
Key terms
- Volatility clustering
- Periods of high volatility following each other
- Value at Risk
- Loss threshold at a confidence level over a horizon
- Expected shortfall
- Average loss beyond VaR
- Backtesting
- Checking model predictions against actual outcomes
- Monte Carlo simulation
- Random sampling to model uncertain outcomes
Quick revision
- ARCH, GARCH(1,1); volatility clustering.
- Normal vs fat-tailed distributions.
- Parametric, historical and Monte Carlo VaR; expected shortfall; backtesting.
- Hypothesis tests in finance; event studies.
- Monte Carlo steps; GBM price paths; option pricing.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.What is volatility clustering?
- Q2.Define Value at Risk.
- Q3.Compute one-day 95% VaR for ₹1 crore with daily σ of 2% (z = 1.65).
- Q4.What is expected shortfall?
- Q5.What is the Jarque–Bera test used for?
- Q6.State two uses of Monte Carlo simulation in finance.
Long-answer questions
- Q1.Explain ARCH and GARCH models of volatility.
- Q2.Explain methods of estimating Value at Risk with an example.
- Q3.Discuss hypothesis testing in finance.
- Q4.Explain Monte Carlo simulation for risk analysis and option pricing.
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