What the ratio is
Divide ETH’s at-the-money implied volatility by BTC’s and you get a number that has spent most of history above one: the market pricing ether as the higher-beta asset. The interesting information is the RANGE — the ratio compresses toward parity when markets treat the two as one macro trade, and stretches when ether-specific risk (upgrades, ETF questions, DeFi stress) trades on its own clock.
A positioning read, not just a fact
Because both legs come from deep, real books, the ratio is priced by hedgers with money at stake — a cleaner beta gauge than any narrative. A stretching ratio into strength says options desks expect ETH to lead; compression during a rally says the upside is being priced as a single-market move. Either way it hands you the one-trade-or-two answer for the majors, continuously.
The alt shadow
The ratio also proxies for everything without a book: when ETH vol stretches over BTC, the market’s appetite for beta is rising, and the bookless alts usually amplify whatever that appetite does next. It is the closest thing the options market offers to an altseason gauge.
Reading it
Track the ratio’s level against its own history, and its direction against the tape’s. Extremes fade; regime shifts trend; and a divergence between the ratio and the alt tape is the market disagreeing with itself — worth attention every time.