Investors got an early fireworks show in the stock market on Friday as the indexes kept chugging higher, with the S&P 500 up nearly 20 points in the final hour of trading before the long holiday weekend.

A better-than-expected ISM manufacturing survey for June lit a fire under stocks on Friday.

SPDR S&P 500 ETF (NYSE: SPY) was on track to close the week with a nearly 6% gain, but some technical analysts see a classic bearish pattern emerging in the tracking index.

Stock ETFs have run the table, while Treasuries have fallen every day every day this week as markets see the end of the Federal Reserve's second round of bond purchases, known as "QE2." (See "Treasury, Stock ETFs Diverge.")

The iShares Barclays 20+ Year Treasury (NYSE: TLT) is down 3% for the week, and ETFs that short bonds have benefitted from higher yields. (See "ETF Spotlight: ProShares UltraShort 20+ Year Treasury.")

In particular, yields on five-year notes have soared this week, punishing ETFs that focus on this part of the Treasury market. (See "Treasury ETFs Damaged.")

In stocks, the bears are licking their wounds after the rally this week but may be clinging to a potential "head and shoulders" pattern in the S&P 500.

"The S&P 500 is close to painting a perfect head and shoulders pattern on the six-month chart," writes Scott Rubin at Benzinga.com.

The "left shoulder" was the February high, while the "head" was the multiyear high in late April, he explained, adding that the pattern would be complete if the index trades up to around the 1,340 area for the "right shoulder" and then sells off.

The session high for the S&P 500 was 1,340 on Friday.

"Obviously, this pattern may not be complete, but it is certainly something to watch," Rubin said. "Currently, sentiment has gone from very bearish to very bullish, and many market participants are looking forward to a strong second half. While the downtrend has been convincingly broken, the head and shoulders pattern developing is something to watch."

The head and shoulders pattern is a common trend-reversal pattern, according to Investopedia.com.

On the other hand, the S&P 500 is sending bullish signals by bouncing at its 200-day moving average. This week's rally also pushed the benchmark over its 50-day moving average. (See "S&P 500 ETFs Survive Tests.")

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