I've come across this many times as I've traded double and triple ETFs. And you are correct in that the double of price each day is reset every day. So yes not just on a double bull or double bear Silver but Crude,Nat Gas or anything done this way is ONLY for 'short term trading' not ever long term as it will erode much the same as an option. They were never designed for long term trading. In fact historically a trader would have far better odds shorting BOTH double bull AND double bear ETFs as a rule of thumb and watch them erode in value. Notice on my ZSL chart where it says at the bottom on the page with an arrow 1 for 4 split. That means price eroded so low that instead of letting it go to zero they gave you one share of ZSL for every 4 you had to bring the price above next to nothing. So for every 100 shares a trader had then they gave you 25 back of the newly price one due to the price erosion. That's what happens with double ETFs. Again they were never designed to be held for long periods of time and many traders have found this out the hard way as most traders marry their trades and don't want to accept being 'wrong' when in the red. Ego is an expensive quality to have. I've traded this 'briefly' now and again and don't stick around for long. Same as double bull and double bear Oil and NG trades.