NEW YORK (TheStreet) -- Stocks have endured a volatile week with benchmark indexes whipsawing from positive to negative and back again as earnings, the European Central Bank and unpredictable oil prices influenced trading.

The S&P 500 fell 0.55% and the Dow Jones Industrial Average slid 141 points on Friday, giving back some of the gains achieved in the previous session as markets rallied on the ECB's quantitative easing announcement. The Nasdaq climbed 0.16%, boosted by Starbucks (SBUX) which climbed on quarterly revenue growth in the double digits.

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Though a bumpy ride in this holiday-shortened week, the S&P 500 did manage to climb 1.6% over the past four sessions, the Dow added nearly 1%, and the Nasdaq jumped 2.7%.

But the unpredictable moves are likely far from over as Wall Street looks toward possible outcomes when the Federal Reserve meets for its monthly two-day meeting on Tuesday.

"The most overanalyzed data in 2015 will be the Fed announcements and the meeting notes," said David Lafferty, chief market strategist for Natixis Global Asset Management. "In the near term, all this reading of the tea leaves is going to create a lot of stock volatility."

Last month, Fed Chair Janet Yellen replaced the central bank's pledge to wait for a "considerable time" to raise rates to a promise to be "patient." Analysts' expectations vary widely on when a hike could occur, but common thought is that one won't occur until the second half of the year.

"Time is running out for the Fed to alter its rhetoric on the rapidly evolving outlook for inflation and inflation expectations," said Morgan Stanley economists in a note. "That said, we think the January meeting is too soon."

Of course, that uncertainty won't breed stability for the markets. But, as Azzad Asset Management's Fatima Iqbal argues, perhaps that isn't a bad thing. "Every investor has to take a look at where they are in their investment cycle and how much risk they can really take [but] for long-term investors, this is a great opportunity ... to take advantage of lower prices," she said in a call.

Crude oil prices continued to see big swings over the week, most recently rallying after the death of Saudi Arabia's King Abdullah overnight. However, gains were short-lived as no change in production policy from OPEC's biggest producer was seen as likely. West Texas Intermediate slid 1.9% to $45.41 a barrel.

"Given the king's deteriorating health of late and that his successor is not likely to tinker with Saudi's oil policy, prices are calming down again," said Matt Smith, a Schneider Electric commodity analyst. "The new Saudi king has decided to retain the services of Ali Al-Naimi, Saudi's oil minister -- hence Saudi's stance of market-grabbing as opposed to defending prices remains intact."

On the economic calendar next week, investors will digest durable goods orders and new home sales for December on Tuesday and fourth-quarter GDP data out Friday is expected to fall back to 3.1% from the previous quarter's 5% growth.

It's a busy week on the earnings calendar for tech companies with Microsoft (MSFT) and Texas Instruments (TXN) due Monday after the bell, Apple (AAPL) and Yahoo! (YHOO) on Tuesday evening, Facebook (FB) and Qualcomm (QCOM) on Wednesday afternoon, and Amazon (AMZN) and Google (GOOGL) after market close Thursday.

Greece could also throw a curveball to European markets at the beginning of next week following the country's presidential elections on Sunday. Opinion polls suggest anti-austerity party Syriza is in the lead. If they are elected, this could trigger a degree of panic as markets question whether the new government will keep to the terms of Greece's bailout package.

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--Written by Keris Alison Lahiff in New York.