Arbitrage-free
Priced so that no riskless profit is available from combining it with other instruments. An arbitrage-free rate tree or model is one fitted to reproduce the market prices of benchmark bonds.
Where you will meet it
Arbitrage-free appears in 6 learning outcomes on the CFA syllabus. A few of them:
- Value a bond by discounting at spot rates
“Pricing with spot rates discounts each cash flow at the rate appropriate to its own date, which is the arbitrage-free value: any other price could be exploited by stripping the bond into its component payments or reconstituting it from them.”
- Explain the idea of valuing a fixed-income instrument so that no arbitrage is possible
“An arbitrage-free value is the price that leaves no riskless profit available.”
- Use a two-period binomial model to value an interest rate option and explain the result
“Interest rate options use an arbitrage-free tree of one-period rates, with probabilities of 0.5 on each branch.”
- Explain how a Monte Carlo simulation of forward rates works and where it is applied
“The model must first be made arbitrage-free: if it misprices benchmark bonds, a constant drift adjustment is added to the simulated rates until those bonds are priced correctly.”
Practise it
Practise arbitrage-free until it is automatic: questions that explain every wrong option.
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