The 200-day simple moving average is turning out to be a tough hurdle for exchange traded funds indexed to the S&P 500.

The iShares S&P 500 (NYSEArca: IVV) slammed into resistance again Thursday at the key technical level in a volatile market driven by reports out of Europe and speculation on Friday’s debt crisis summit.

The U.S. stock index has struggled to get above the 200-day average during several attempts in recent months. The S&P 500 fell 2.1% in Thursday’s sell-off. [S&P 500 ETFs Look to Break Out]

Standard & Poor’s U.S. investment policy committee in a note this week said it expected a minor near-term dip in the major indices before the next leg higher begins.

“We see the S&P 500 declining to the 1,210-1,230 region over the next week, followed by a strong rally into heavy overhead supply up in the 1,350-1,370 area by the end of 2011 or into the first quarter of 2012,” S&P said.

The S&P 500 closed at 1,234 on Thursday.

“This forecast depends on the U.S. Dollar Index, which appears to be tracing out a double top,” the committee added. Stocks and the dollar have tended to move in opposite directions lately.

PowerShares DB US Dollar Bullish (NYSEArca: UUP) gained 0.5% on Thursday.

Meanwhile, from a technical perspective, S&P thinks Treasury bonds look “very susceptible” to a major correction.

“The 10-year Treasury yield is working on an inverse head-and-shoulders formation and would be completed by a move above the recent high of 2.4%. Sentiment toward Treasury bonds has been bullish for months, while Commitment of Traders (COT) data is becoming unfriendly to Treasuries, in our view,” the committee added.

The iShares Barclays 20+ Year Treasury Bond (NYSEArca: TLT) gained 1.3% on Thursday. [Investors Bet Against Treasuries with ETFs]