BALTIMORE ( Stockpickr) -- A data error that showed the S&P 500 down 97 points in the last two minutes of trading on Monday had traders nervous as some wondered if the high-percentage move was for real. The bad tick showed up on most data sources, including most brokerage sites and trading platforms, and the source of the problem has yet to be named as of this writing, much to the chagrin of a few Twittering traders.

Most brokerage sites had the tick error fixed shortly after the market close, though Google Finance still showed the error as of 8 p.m. Wednesday evening.

In reality, the S&P gained modestly for its sixth straight session, which means that 2010 marks the longest streak of gaining days for the broad-based index since 1987.

With 2010 off to a solid start, it's time to turn to the technicals of the market for stocks that are set up for a breakout.

Technical analysis is a way for investors to quantify qualitative factors such as investor psychology based on a stock's chart patterns and trends. Once the domain of cloistered trading teams on Wall Street, technicals can help top traders make consistently profitable trades and can aid fundamental investors in better planning their stock execution.

But all too often, investors don't know where to start. So every week, Stockpickr takes a look at stocks that could be staging a technical move soon and compiles a portfolio of promising Technical Setups.

Here's a look at this week's stocks.

In recent years, United Online ( UNTD) has diversified its business from what was formerly a free and discount dial-up Internet provider to a network of online properties that sell high-margin products and provide recurring, subscription-based revenue.

But it hasn't been completely clear sailing for United Online in the last few months. Shares took a sizable hit back in August following a third-quarter earnings release that didn't impress investors, and the stock slid even further in mid-December after a Senate probe cited United Online properties Classmates.com and FTD for dubious business practices.

From a technical standpoint, there are more roadblocks in the stock's way right now. Shares formed a bearish head-and-shoulders pattern toward the end of 2009 -- a feature that exacerbated the Senate news -- and fell hard in November. And right now, with the stock's 50-day moving average about to cross under its 200-day average, another bearish sign, United doesn't show many signs of recovery this month.

The stock is pushing hard against its 50-day average right now. Expect it to continue to follow it lower this week.

Utility holding company Ameren ( AEE), like United Online, has faced some tough fundamentals lately.

But unlike the first stock on this week's list, Ameren is exhibiting some potentially bullish technicals that could present investors with upside in the next week.

With Ameren, the Fibonacci retracements are the technical indicator worth watching. Fibonacci retracements map key price levels at Fibonacci ratios, the naturally occurring points discovered by 13th-century Italian mathematician Leonardo Fibonacci. With stocks, Fibonacci retracements map out areas of organic support and resistance (which you can see at several points in the chart above) -- including a support level at $26.75.

With a pullback from a mid-term high currently underway, the first sign of a bounce off of the $26.75 support level marks the buy trigger for this trade.

Semiconductor material supplier ATMI ( ATMI) has been trading in a wide range in the last couple of months, but a recent change of trend suggests that investors could be in for a bullish continuation in the near term.

ATMI supplies specialized components and materials to semiconductor and flat-panel display manufacturers, a business that took a moderate hit in 2008 as consumers' discretionary income contracted and savings increased. Now, in 2010, with consumer and business customers more apt to shell out money for new electronics, ATMI is in the midst of recovery.

The same is true of the company's stock, which has rallied hard from early-November lows. ATMI's shares saw a double-top in the second half of the year, a bearish pattern that signals lower share prices are ahead. Sure enough, shares tumbled double-digits in the last quarter of '09, and shares have only just recovered. But a breakout above a key resistance level followed by consolidation suggests that shares are headed higher.

The consolidation channel is weak for ATMI right now. Don't buy shares until it makes its next strong upward tick.

To see these plays in action, check out the Technical Setups for the Week portfolio on Stockpickr.

-- Written by Jonas Elmerraji in Baltimore.

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Jonas Elmerraji is the editor and portfolio manager of the Rhino Stock Report, a free investment advisory that returned 15% in 2008. He is a contributor to numerous financial outlets, including Forbes and Investopedia, and has been featured in Investor's Business Daily, in Consumer's Digest and on MSNBC.com.