Stocks Back on Winning Path; P&G Leads Dow

Stocks resumed their ascent Friday, after snapping the week's winning streak on Thursday, as investors braced for a volatile day due to quadruple witching.

The expiration of four contracts—stock index futures, stock index options, stock options and single stock futures—happens once each quarter and is frequently both a bullish and volatile day on the markets.

Procter & Gamble shares led the Dow after Citigroup raised its rating on the stock to "buy," saying the company is about to get aggressive with pricing to win back market share.

There were a slew of other upgrades today:

Apple shares rose after an upgrade to "outperform" from Macquarie, which said it is "increasingly confident that Apple has negotiated the worst of the consumer recession" and that the iPhone would continue to dominate the smartphone market next year.

And Dow oil component Chevron got an upgrade to "outperform" from Credit Suisse.

Homebuilders Toll Brothers and KB Home advanced after being upgraded by JPMorgan, which said the housing sector will continue to recover in the next two years.

Chip stocks got a boost after SanDisk was upgraded by Bank of America-Merrill Lynch to "buy."

Among the few downgrades today was Genzyme : Deutsche bank downgraded the stock to "hold" from "buy."

And Palm shares fell more than 3 percent after the hand-held device maker beat analyst estimates but disappointed with its outlook.

Thursday's modest losses notwithstanding, stocks are on an impressive roll for a month that's historically the worst for stocks. The Dow is up more than 3 percent for September so far, the S&P 500 has chalked up a gain of 4.4 percent, and the Nasdaq is up 5.9 percent.

Both the S&P and Nasdaq are on pace for their seventh consecutive monthly gains.

Banks retreated, including Bank of America and Citigroup , after a quick pop at the open.

And General Electric shares , which crossed $15 earlier this week and then rallied straight up to $17, pulled back.

Small-cap Arena Pharmaceuticals rallied after the experimental obesity drug fell short of one FDA guideline but met another and analysts said data indicated the drug was safe.

Dow component Hewlett-Packard has a new board member: Marc Andreesen, best known as the co-founder of Netscape. He's also on the boards of eBay and Facebook.

- Peter Schacknow contributed to this report.