Stocks advanced on Friday, putting the S&P 500 on track for back-to-back weekly gains for the first time since early July after better-than-expected retail sales and results from Google .

Increased optimism that a solution to the euro-zone crisis would happen added to the positive mood.

The benchmark S&P index is up 13 percent from the October 4th intraday low of 1,074.77, which had temporarily tipped it into bear market territory.

Google Inc led the Nasdaq higher as shares jumped 5.9 percent to $592.16, a day after its results blew past Wall Street's expectations, helped by strong advertising sales and deft cost controls.

Apple Inc rose 2.6 percent to $419.23 as the newest version of its iPhone went on sale across the country.

There are these positive catalysts that may be in place -- earnings being one and a more formalized policy action out of Europe, more clarity there, said Natalie Trunow, chief investment officer of equities at Calvert Investment Management in Bethesda, Maryland, which manages about $14.8 billion.

To the extent earnings come through as expected or better than expected, which we think is more likely to be the case, then that will provide sufficient support for the equity markets, she said.

The Dow Jones industrial average <.DJI> was up 105.01 points, or 0.91 percent, at 11,583.14. The Standard & Poor's 500 Index <.SPX> was up 13.63 points, or 1.13 percent, at 1,217.29. The Nasdaq Composite Index <.IXIC> was up 30.83 points, or 1.18 percent, at 2,651.07.

French and German officials are trying to put flesh on the bones of a crisis resolution plan in time for a European Union summit on October 23, overshadowing Standard and Poor's cut of Spain's credit rating, a move that underlined the challenges facing Europe's finance ministers.

Among U.S. economic data, September retail sales rose 1.1 percent from a month earlier, beating the median forecast in a Reuters poll for a rise of 0.7 percent. Sales growth during August was revised upward to 0.3 percent.

(Reporting by Caroline Valetkevitch; Additional reporting by Ryan Vlastelica; Editing by Jan Paschal)