Today: First week of 2013 is a good one for Wall Street, as new employment numbers show grinding progress. Meanwhile, Apple (AAPL) and Zynga shares shoot in opposite directions. Also: Google (GOOG) may face a tougher antitrust probe in Europe.

Encouraging jobs report helps S&P 500 to 5-year high

Traders work on the floor of the New York Stock Exchange in New York, January 4, 2013. U.S. stocks firmed slightly on Friday after a key U.S. jobs report
Traders work on the floor of the New York Stock Exchange in New York, January 4, 2013. U.S. stocks firmed slightly on Friday after a key U.S. jobs report showed the pace of hiring by employers had eased slightly in December but gave signals of some momentum in the labor market's recovery since the 2007-09 recession. REUTERS/Eric Thayer (ERIC THAYER)

Wall Street ended its best week in six months Friday, as the latest jobs report found slow but steady economic improvement.

For the shortened week, the tech-heavy Nasdaq index led the way, with a 4.8 percent increase; the Standard & Poor's 500 was up 4.6 percent; and the Dow Jones industrial average rose 3.8 percent.

Stocks had surged Wednesday, after Congress reached an agreement to avoid the "fiscal cliff," which could have had devastating economic results. All three major indexes made incremental gains Friday, led by the S&P 500, which hit a five-year high and rose almost half a percent.

Apple and Zynga were on opposite sides of the stock spectrum Friday. Word that some holiday sales were down added to lingering worries about Apple's product line, sending shares in the Cupertino tech giant down 2.78 percent, or $15.10, to close at $527, sending its market cap again below the $500 billion mark. Shares in San Francisco gaming company Zynga, on the other hand, soared 9.13 percent Friday, up 22 cents to close at $2.63 after reporting encouraging user numbers for its "FarmVille 2" game.

The market was reassured by Friday's federal jobs report, which fell along expected results. The report found that while the unemployment rate remained unchanged at 7.8 percent, 155,000 jobs were added in December. While that number of new jobs is about average for the past year, there were fears that fiscal cliff worries would discourage companies from hiring last month. "This shows the economy is chugging along," Tom Porcelli, RBC Capital economist told Reuters.

The economy showed more improvement in other areas: Layoffs are declining, the housing market is improving, manufacturing and spending is up and the number of people filing for unemployment hit a four-year low in December.

Google may face tougher antitrust probe in Europe

Google may have dodged a bullet Thursday when the Federal Trade Commission announced it was ending an 18-month-long antitrust investigation with no penalties, but the Mountain View Internet giant is not out of the woods yet. The European Union, which is conducting a similar investigation, said Friday the FTC's ruling would have no bearing on its case.

"We have taken note of the FTC decision, but we don't see that it has any direct implications for our investigation, for our discussions with Google, which are ongoing," European Commission spokesman Michael Jennings said in a statement, according to Reuters. The two-year-long European probe is centered around charges that Google shows unfair bias toward its own services in search results. Google has been given a mid-January deadline to address the complaints, and faces a fine of up to $4 billion if found guilty of anti-competitive practices.

Experts believe the European investigation will demand tougher concessions than the FTC. "History shows that competition law is applied to monopoly power more stringently in the EU than in the U.S.," Jacques Lafitte, head of the competition practice at Brussels-based Avisa Partners, told the New York Times. And Google's European market share -- with 83 percent of Internet searches, compared to 67 percent in the U.S. -- may strengthen the perception of a monopoly:

Microsoft has been among the Google critics complaining the loudest, and Microsoft vice president and deputy general counsel Dave Heiner, who called Thursday's FTC's decision "weak," is holding out hope for a more favorable result from the EU probe. "The good news is that other antitrust agencies, within the United States and overseas, are still examining Google's conduct. In Europe Vice President Almunia has made clear that he will close his investigation of Google only with a formal, binding order that addresses search bias and other issues," Heiner wrote in a blog post.

Investors responded positively to the FTC agreement, boosting Google shares almost 2 percent Friday, up $14.30 to close at $737.97.

Silicon Valley tech stocks

Up: Google, Oracle (ORCL), Cisco (CSCO), eBay (EBAY), Yahoo (YHOO), Facebook, LinkedIn

Down: Apple, Intel (INTC), Netflix

The tech-heavy Nasdaq composite index: Up 1.09 , or 0.04 percent, to 3,101.66.

The blue chip Dow Jones industrial average: Up 43.85 or 0.33 percent, to 13.435.21.

And the widely watched Standard & Poor's 500 index: Up 7.10, or 0.49 percent, to 1,466.47.

Check in weekday afternoons for the 60-Second Business Break, a summary of news from Mercury News staff writers, The Associated Press, Bloomberg News and other wire services.