FRM Part II · FRM Exam Part II · Volatility Smiles and Volatility Surfaces
A risk analyst compares implied volatilities of EUR/USD options across strikes and observes a U-shaped pattern, with out-of-the-money calls and puts both having higher implied volatility than at-the-money options. Which feature of the underlying exchange rate distribution, relative to the lognormal assumption, best explains this foreign currency smile?
The U-shaped smile arises because the exchange rate distribution has fatter tails than the lognormal distribution on both sides. Extreme moves in either direction are more likely than Black-Scholes assumes, so out-of-the-money calls and puts are priced with higher implied volatility than at-the-money options.
- AThe exchange rate has fatter tails than a lognormal distribution, with both extreme moves more likelyCorrect
- BThe exchange rate has a thinner right tail and a heavier left tail than lognormal
- CThe exchange rate volatility is constant and the distribution is exactly lognormal
- DThe exchange rate has thinner tails than lognormal, with extreme moves less likely
Explanation
A symmetric U-shaped smile in currency options indicates that both tails of the exchange rate distribution are heavier than lognormal. Heavier tails raise the value of deep out-of-the-money options and so raise their implied volatility. A left-heavy and right-thin distribution would produce a skew, not a smile.
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