Lets take a leveraged etf L with a leverage ratio of beta and model it's [sic] relationship with the underlying index returns.
To start, assume that underlying index is following a brownian motion process:
dS/S = vol * dW + m*dt
where W is Wiener process and m is drift. You would then express it's [sic] return process as:
dL/L = beta * dS/S - [ (beta - 1)* rate + fees ] * dt
= (rate - fees) * dt + beta * vol * dW
so, expressing the expected returns of the LETF in terms of the underlying index and it's [sic] vol:
Lt/L = (St/S) ^beta * exp{ -[ rate*(beta-1) + fees] * time - variance * time * (beta^2-beta)/2 }
the second term in the exponent implies that return of the leveraged ETF is going to be negatively related to variance of the underlying index.
If the return of a levered ETF is "negatively related to variance of the underlying index," then is a levered ETF on a more volatile underlying going to return less than one on a less volatile underlying? (Rhetorical question -- the answer is: of course not).
. You need a good broker to trade them that charges very low commissions .