The 25-delta risk reversal is the difference between the implied volatility of the 25-delta call and that of the 25-delta put, ; as a trade, it is a long call and a short put (or the reverse). The 25-delta strangle is a long 25-delta call and a long 25-delta put; its volatility quoted over the at-the-money volatility is the 25-delta butterfly.
Exemplos
Example 19.6 (Two smiles from one screen)
USDJPY three months: ATM 9.5%, risk reversal (dollar puts over), butterfly 0.3. By Equation 19.1 the 25-delta dollar call is at 9.2% and the put at 10.4%. With regular spot deltas their strikes are 160.85 and 150.71; with premium-adjusted spot deltas, the pair’s convention, 160.68 and 150.52. A trader who priced the 150.71 put at 10.4% while the market meant 150.52 would misprice it by the smile’s slope over 19 pips of strike (Figure 19.2).