25Δ Risk Reversal
RR = IV(25Δ Call) − IV(25Δ Put). Crypto-desk standard for implied-volatility skew.
25Δ Risk Reversal (RR) is the difference in implied volatility between a 25-delta call and a 25-delta put at the same expiration:
RR = IV(25Δ Call) − IV(25Δ Put)
Expressed in volatility points. Negative values mean puts are richer (market paying for downside); positive values mean calls are richer (market paying for upside).
The 25Δ RR is the crypto-desk standard for quoting vol skew — it's the number Deribit, Paradigm, and institutional vol books use. It's the implied-vol-price cousin of the put/call ratio.
See also: 25Δ RR (Risk Reversal)