At work someone just the other day was talking about something like this. He wanted to buy UWT but was afraid it would do a R/S. I explained would you be worried about the S&P 500 doing one, he said no. I said then if you bought the SPY would you worry, he said no because I knew he understood the correlation of the two. I said well same same. Oil is to UWT as XOP is to GUSH as GDX is to NUGT as SPX is to SPY etc etc.