There are some 2x leveraged funds where the manager offers a Bull and Bear pair. One is Long (and 2x leveraged) and one is Short (and 2x leveraged).
Now, you would expect them to have the OPPOSITE returns, for example, one up (say) 30% over a year and one down 30%, right? Not so, owing to the leverage and daily rebalancing, the likely returns would be a 20% gain and a 40% loss!!
It all has do to with a 1.0% loss, requiring a 1.01% gain (from the lower level) to break-even. Leveraging requires the fund buy more shares on an up fluctuation and sell shares on a down fluctuation to maintain the 2x leverage. Effectively "buying high and selling low" on daily fluctuations.
Better to buy an leveraged fund than a leveraged fund!!
Or an investment trust leveraged with a fixed term loan (and not rebalancing daily like an ETF).
(Of course, the correct strategy would be to SHORT both the long and short leveraged ETF - but that idea is so popular with hedge funds and profession investors that your broker won't be able to find any stock to borrow for your short sales.)