Quote from winstontj:
wow - a lot of mis-information here in this thread from the first post (yahoo article) to the suggestions as to why the pairs don't always track equally.
All of these things are index based ETFs and most have "optimized baskets" which seek to accuratley track the underlying index - but don't always track perfectly.
Most often when you see a pair's (bull & bear same index) tracking or intra-day price deviate from where it should be it can contributed to the previous day's close. If one closed at a discount or premium it will usually self correct at the next open - leaving one right off the bat trading up or down from the index because of the correction.
Look in the funds' prospectus - you will find that the bull & bear pairs are ALWAYS comprised of the same thing, only one is short and one is long so the holdings will be different, though they will still track the same index - at least in my experience.
quick correction - third paragraph should read
Most often when you see a pair's (bull & bear same index) tracking or intra-day price deviate from where it should be it can contributed to the previous day's close. If one closed at a discount or premium it will usually self correct at the next open - leaving one right off the bat trading up or down ON THE DAY because of the correction. If the correction put the ETF up or down by x% you will notice that it will remain that way for the day
