If the S&P 500 isn't enough for you, maybe you just need to juice it up.

ProFunds Group is expanding its already massive portfolio of ProShares exchange-traded funds, including yesterday's debut of UltraPro S&P500 (NYSE:UPRO). The ETF aims to deliver 300% of the S&P 500's daily gains. But cheer up, bears: UltraPro Short S&P500   (NYSE:SPXU) targets triple the daily results of shorting the same index.

If this sounds like the kind of high-octane pizzazz that your portfolio is longing for, do the math. These ETFs-on-steroids that hit the market may sound great in theory, but reality hasn't been kind to them.

ProShares already has a pair of ETFs that promise to double the daily performance of the S&P 500. How are they holding up against the SPDR Trust (NYSE:SPY), which simply mirrors the popular index?

 

2009 Return

SPDR Trust

2.0%

Ultra S&P 500 (NYSE:SSO)

(0.5%)

UltraShort S&P 500 (NYSE:SDS)

(22.1%)

Returns exclude dividends.

See the problem? The doubled-up long fund hasn't delivered a 4% gain year to date. The jacked-up short fund is off by far more than 4%. These vehicles may be great for nailing a single day's return, or occasionally landing within the ballpark of an entire week's run. But they can be catastrophic over the long haul, particularly if they get whipsawed during volatile markets. Go figure: These magnets of speculation can ironically crumble at the first signs of volatility.

Need a little more proof?

Direxion Daily Financial Bull 3x Shares (NYSE:FAS) and Direxion Daily Financial Bear 3x Shares (NYSE:FAZ) play both sides of the financial-service stocks within the Russell 1000 index -- they swing for 300% of the movements.

At least one of them has to be a big winner in this roller-coaster market for banking stocks, right? Wrong. The bullish fund is trading 64.6% lower than it was when the year began. If you think that's bad, the bearish fund is off by a whopping 86.5%. 

If you're a speculator looking for a day-trade gamble, these may be your lottery tickets. However, if you're a serious long-term investor, you don't want to get anywhere near these funds. 

The numbers say it all. You'll triple your trouble before you triple the market's returns.

Some other reads that may double -- or triple -- your ETF knowhow:

Longtime Fool contributor Rick Munarriz always seems to have a fund or two in his portfolio, but he owns no shares in any of the companies mentioned in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. Try any of our Foolish newsletter services free for 30 days. The Fool has a disclosure policy.