I have an SDS 5 minute chart on my computer right now and see that the price is right at support from 8 days ago. I just looked at the $SPX however and see that the index is at 925 vs a high of 930 from 8 days ago. I had no idea the time decay effect was this extreme. (actually maybe it's even worse: http://marginalizingmorons.blogspot.com/2009/02/measuring-etf-decay.html ) this raises a few questions: -in people's expericence is the above example typical decay? -are support and resistance therefore useless in trading these ETF's if your time frame is more than 2-3 days? -Are trendlines also useless or are they safer? - do people use the index charts rather than the ETF charts for support, resistance, and trendlines while trading the ETFs? thanks.