I believe that these four questions are all duplicates of each other:
- Why buying an inverse ETF does not give same results as shorting the ETF
- Why an ETF mirrors the underlying index on a day to day basis but not on a long term basis
- Investing in a leveraged index ETF for retirement. Risky?
- Why are daily rebalanced inverse/leveraged ETFs bad for long term investing?
When writing my answer for the last question (a while ago, now), I noticed that there was quite a bit of overlap with other questions, so I included links to them in my answer. But the more I look at it, the more I realize that really all of these questions should be combined or marked as duplicates or something. I'm not sure of the best approach to take, as there are a lot of good answers spread amongst the questions. I'd just start flagging some as duplicates, but I feel biased about picking one since I wrote one of the somewhat-highly-voted answers.
- Select one of these questions (somehow) and mark the others as duplicates?
- Attempt to create a new canonical question/answer, maybe as a Community Wiki, and mark all four of these as duplicates of it?
- Leave things as they are, since they are all coming at the problem from slightly different perspectives, and nobody else seems to have minded?
- Something else?