More than 60 S&P 500 companies are scheduled to release results next week, including more than half a dozen Dow components. The reports will give the fullest picture yet of how corporations are faring and whether the market can advance further as Fed stimulus begins to recede.

"Given that equities are fully valued and arguably overvalued, we need earnings and revenue to come through to support the gains we've already made," said Jack Ablin, chief investment officer at BMO Private Bank in Chicago. "There's a reasonable chance we could see a 10 percent correction in the event we get some high-profile disappointments."

Earnings for S&P 500 companies are seen rising 7 percent in the quarter, down from the 7.6 percent rate that had been forecast at the start of the year.

While the season started with many financial firms, including JPMorgan Chase & Co (>> JPMorgan Chase & Co.) and Bank of America (>> Bank of America Corp), topping profit expectations, Intel Corp (>> Intel Corporation) sounded a sour note, slumping on a weak revenue outlook. General Electric Co (>> General Electric Company) sold off despite posting higher-than-expected revenue, suggesting blowout results may be needed to justify elevated valuations.

With 10 percent of the S&P 500 having reported results so far, 50 percent have topped earnings forecasts, well below the historical average of 63 percent, according to Thomson Reuters data. More than 67 percent have beaten revenue expectations, above the long-term average of 61 percent.

Procter & Gamble (>> The Procter & Gamble Company), McDonald's (>> McDonald's Corporation), Microsoft (>> Microsoft Corporation), Johnson & Johnson (>> Johnson & Johnson) and Verizon Communications (>> Verizon Communications Inc.) are among the Dow components scheduled to report next week. Texas Instruments (>> Texas Instruments Incorporated) and Starbucks Corp (>> Starbucks Corporation) are also on tap.

The U.S. stock market will be closed on Monday for the Martin Luther King Jr. holiday.

WATCHING FOR SIGNS OF BUSINESS SPENDING

BMO's Ablin said that results from more cyclical groups would be especially important for insight into the strength of the overall economy.

"The next leg of the cycle has to be driven by business spending," he said. "I'm looking for clues that businesses are taking their excess cash flow and spending it, which means tech and industrial reports will be very important, especially any outlooks they offer."

Another key name will be Netflix Inc (>> Netflix, Inc.), the S&P 500's biggest gainer in 2013. The online movie renter's stock nearly quadrupled last year, raising concerns it may follow the same path as another of 2013's momentum favourites, Best Buy Co Inc (>> Best Buy Co., Inc.). On Thursday, the electronics retailer's stock suffered its worst daily decline since 2002 after posting weak holiday sales and giving a downbeat margin forecast.

Jonathan Krinsky, chief market technician at MKM Partners in Greenwich, Connecticut, said the market was "absolutely vulnerable to a pullback on big disappointments," though the S&P 500 might find support at its 50-day moving average, about 1.7 percent below Friday's close at 1,838.70.

"If we take that out, that would be the first time we've made a lower low in a while," he said. "That could push us to retest the December low around 1,770."

In the latest week, the Dow rose 0.1 percent, the S&P 500 slipped 0.2 percent and the Nasdaq climbed 0.6 percent. Both the Dow and S&P 500 are within striking distance of all-time highs.

The forward price-to-earnings ratio for the S&P 500 is about 15.22, according to Thomson Reuters data, roughly in line with the historic average. While that suggests valuations are not tremendously stretched, further steep gains may be difficult to come by.

"We're much more likely to fall on negative earnings than we are to rally on strong ones," said Bruce Bittles, chief investment strategist at Robert W. Baird & Co in Nashville. "There's much more downside risk than upside at these levels, and that will probably be the case until we work off some of the excess out there."

Next week will be a light one for economic data, with Wednesday's read on December existing home sales perhaps the biggest report. Sales are forecast to edge up for the month, according to economists polled by Reuters.

(Wall St Week Ahead runs every Friday. Questions or comments can be emailed to: ryan.vlastelica(at)thomsonreuters.com)

(Editing by Nick Zieminski and Jan Paschal)

By Ryan Vlastelica