Index Exchange Traded Funds

I'm becoming more and more interested in exchange traded funds (ETFs) as a way to capture the movement of the market without having to actively manage my account.  As mentioned in earlier posts, I'd hoped to dabble in Index mutual funds and/or ETFs as part of my evolving strategy.

While I continue to think these have a place in my strategy, I remain mystified about how I would actually do this.  In fact, this morning, I got quite a shock to my assumption about the behavior of these funds. 

As an experiment, I compared the yields of four ETFs which as based on the S&P 500.  My first experiment supported this.  When I compared the yields between SPY, IVV and the S&P Index itself, I found them almost indistinguishable. 

Then I compared some other ETFs and found quite a surprise.  When I compared, SPY, SSO and UPRO, I found that that there was some kind of multiplier effect at work where the yields of some ETFs are doubled and tripled.  So clearly all S&P 500 ETFs are not the same and there are some very deliberate actions afoot to provoke this multiplier.

Next steps, I need to figure out why the yields are different and which (if any) of these funds will best complement my current strategy.  It's easy to see that a very bullish or very bearish investor could benefit from one of the multiplied funds, but I'm not sure how this fits into my balancing act where I hope to be cope with market upturns or downturns.

hmmmmmm.