Title: Decoding Volatility Surfaces on the Wilmott Forums: A Deep Dive into Risk Reversals and Butterflies

The Hidden Cost of Volatility Drag

Volatility is a crucial factor in options trading, yet its impact can often be underestimated. On the Wilmott Forums, a question was posed about the applicability of certain formulas for different deltas, shedding light on an important aspect of volatility surfaces.

Unraveling Risk Reversals and Butterflies

The formulas in question involve risk reversals (RR) and butterfly spreads (BF). RR is a strategy that compares the price of a call option with a corresponding put option, both having the same strike price but different maturities. A butterfly spread, on the other hand, involves three options: two calls and one put, all with the same expiration date but different strike prices.

The Application Across Deltras

The question on the forum was whether these formulas hold for deltas beyond 25D. The consensus was that they do apply to any delta, provided the butterfly has the same strikes as the risk-reversal. However, this is not usually the case in foreign exchange markets, making the formula an approximation to market butterflies.

Implications for Portfolios and Key Assets

For investors, understanding these formulas can help in calculating option prices more accurately. The formulas can be used with implied volatilities for various deltas, which have been calculated using risk reversals and butterflies. However, the interpolation method used must be chosen carefully to respect non-arbitrage in the space direction.

Actionable Insight

Armed with this knowledge, investors can better navigate the complex world of options trading. By understanding the applicability of these formulas across deltas and the importance of choosing the right interpolation method, they can make more informed decisions and potentially enhance their portfolios' performance.