The past week mostly continued the trend of 2012 treating investors right -- though the gains weren't nearly as pronounced as they had been through the first few weeks of the year. While positive earnings news kept Mr. Market optimistic on the whole, there were some serious concerns that weighed on investors toward the back end of the week. Europe continues to be a primary worry, and Greece in particular is causing some nail-biting as it continues its tug-of-war with private investors to work out a debt compromise. In the U.S., meanwhile, the economic outlook took a hit when the advanced reading on fourth-quarter GDP growth came in below estimates.

By the time the dust had settled, the Dow Jones Industrial Average (INDEX: ^DJI) slipped by 0.5%. However, the broader Russell 3000 added 0.4%. The earnings results helped some sectors hurdle the average, but defensive industries suffered as investors continued to focus on the potential for economic recovery.

The 3 Worst-Performing Sectors

Russell 3000 Sector

Weekly Price Change

Month-to-Date Price Change

Telecom (0.4%) (0.4%)
Consumer Staples (0.3%) (0.2%)
Utilities 0% (0.6%)

Source: S&P Capital IQ. Weekly price change is Jan. 20-Jan. 27. Monthly price change is Dec. 30-Jan. 27.

Think it's just natural gas companies that are being hurt by low natural gas prices? Think again. With low gas prices discouraging new capital spending by explorers, the headaches of the industry are also hitting companies such as CARBO Ceramics (NYSE: CRR). In its fourth-quarter earnings press release, CEO Gary Kolstad highlighted that the full year was a record one for CARBO, but the declines related to its natural gas customers helped keep both revenue and earnings well below Wall Street's expectations.

Momenta Pharmaceuticals (Nasdaq: MNTA), meanwhile, saw its shares dive after a federal circuit court reversed a stay on Watson Pharmaceuticals and its partner Amphastar Pharmaceuticals, allowing the manufacture and sale of a generic version of Momenta's Lovenox. The court's decision seems like a setback for Momenta, but the company still has a pending patent-infringement suit against Amphastar that Momenta's management is confident about.

The 3 Worst-Performing Russell 3000 Companies


Weekly Price Change

CARBO Ceramics (20%)
Twin Disc (20%)
Momenta (20%)

Source: S&P Capital IQ. Weekly price change is Jan. 20-Jan. 27. Includes only companies with market caps of $250 million or more.

Also among the week's worst performers were Corning (NYSE: GLW) and InterDigital (Nasdaq: IDCC). For Corning, the week's 13% drop was driven by disappointing revelations in the company's fourth-quarter earnings report. Though earnings per share for the quarter matched analysts' expectations, the company admitted that it's facing a rough road ahead thanks to tough conditions in the LCD-glass and solar-panel markets.

InterDigital, meanwhile, shook investors after it unsuccessfully ended its search to find a buyer. The wireless-technology company had stoked investors' expectations for a quick cash-out after it hired Evercore Partners and Barclays over the summer. While the fact that it didn't find a suitor could simply mean it was hoping for too high of a price, the announcement sent many investors running and helped push the stock down 17% for the week.

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