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FRM Part II · FRM Exam Part II · Volatility Smiles and Volatility Surfaces

A dealer uses Black-Scholes with a flat 8% volatility to price a one-year 25-delta out-of-the-money EUR call and put. The market shows a symmetric smile, with the implied volatility of those options at 10%. The dealer sells a strangle (call and put) priced at 8% volatility and hedges delta only. Which statement best describes the resulting exposure?

The dealer sold the strangle too cheaply, because the market prices out-of-the-money options at 10% volatility versus the dealer's 8%. The position is short convexity and exposed to large moves in either direction, which are more likely than the lognormal model implies. Delta hedging does not remove this exposure.

  1. AThe dealer is overhedged and profits if the exchange rate stays near the current level
  2. BThe dealer has sold the strangle too cheaply relative to the market and is exposed to large moves in either directionCorrect
  3. CThe dealer has sold the strangle too expensively and gains if tails are fat
  4. DThe dealer has no exposure because delta hedging eliminates all risk

Explanation

The market values the wings at 10% volatility, but the dealer charged the 8% price, which is lower. The dealer is thus underpriced on the strangle and, being short gamma, loses on large moves in either direction, which are more likely than the flat-volatility model implies. Delta hedging does not remove gamma or vega exposure.

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