The Week's Top Stock Gainers

In a yawn-inducing finish, 2011 closed out almost exactly flat with where it started. With such a low hurdle, it was easy for a positive start in 2012 to leave investors with a better gain in the first week of the year than they got from all of last year. The week-one gains didn't come without positive economic news, including a better-than-expected jobs report that showed 200,000 payroll additions and dragged the unemployment rate down to 8.5%.

The Dow Jones Industrial Average (INDEX: ^DJI) gained 1.2% for the week, while the broader Russell 3000 climbed 1.6%. While most sectors rode along with the broad indexes' gains, there were a few that managed much better returns for the week.

Top 3 Performing Sectors

Source: S&P Capital IQ. Weekly price change is Dec. 30-Jan. 6. Monthly price change is Dec. 30-Jan. 6.

Health care was a lagging sector, but don't tell that to Dendreon (Nasdaq: DNDN). Shares spiked 63% to kick off the year after the company said that sales of its cancer drug Provenge tripled from a year ago. The sales growth surprised analysts and investors, both of whom had been concerned after the company pulled its previous sales guidance. Will 2012 be a better year for Dendreon? We'll have to wait and see, but that's a pretty great way to ring in the new year.

A123 Systems (Nasdaq: AONE) got a boost after Fisker Automotive said that it has already fixed most of the cars using potentially faulty A123 batteries. The concern was over a hose clamp in the battery that had the potential to leak coolant and cause a fire. A123's stock continued rising later in the week, after the company announced an agreement to supply batteries for VIA Motors. Does this all mean it's a good time to get revved up about A123? My fellow Fool Travis Hoium isn't convinced.

Top 3 Performing Russell 3000 Companies

Source: S&P Capital IQ. Weekly price change is Dec. 30-Jan. 6.

Also among the week's top performers were Netflix (Nasdaq: NFLX) and InterMune (Nasdaq: ITMN). After a horrid 2011 in which Netflix's stock was pummeled and its management's decision-making was seriously questioned, 2012 started off on a much better note for Netflix investors. A good chunk of the week's gains came after the company announced that it served up an eye-popping 2 billion hours of streaming video to more than 20 million customers during the final quarter of the year. When all was said and done, the stock had tacked on nearly 25% for the week.

Biopharma InterMune, meanwhile, wowed investors when it released preliminary sales results for its drug Esbriet. Sales have been brisk in Germany since the drug's mid-September launch, and the company is looking to add the France, Spain, Italy, and U.K. markets in 2012.

That's it for this week's top-performers recap. If you're looking for some ideas for strong outperformers in the year ahead, The Motley Fool has created a brand new free report titled "The Motley Fool's Top Stock for 2012." In it, my fellow Fools reveal a top pick that's poised for explosive growth ahead. Get instant access -- it's free.