Oil prices rose in volatile trading on Monday on hopes an agreement to cut output could be reached at an OPEC meeting this week but stocks moved lower, putting four-day winning streaks for the S&P 500 and Dow Jones Industrial Average in jeopardy.

West Texas Intermediate crude oil gained 2% Monday to $47 a barrel after trading in and out of positive territory for much of the morning. 

The S&P 500 fell 0.35%, the Dow Jones Industrial Average declined 0.36% and the Nasdaq tumbled 0.28%.

Saudi Arabia suggested over the weekend that OPEC didn't need to reduce output to rebalance the oil market as increasing demand in 2017 would serve to drain a supply glut that has weighed on prices.

"There's so much doubt regarding this OPEC meeting," Stephen Guilfoyle, president of Sarge986, said in a phone interview. "I think there's a lot of smoke here, smoke and mirrors. They'll probably come to some kind of agreement, at least in principle, because they have to because there's a lot of pressure on them."

Saudi Arabia pulled out of a planned meeting on Monday with non-OPEC oil producers, claiming the get-together was pointless until OPEC finalized its production targets. The 14-nation OPEC cartel is scheduled to meet Wednesday in Vienna.

"The price of oil has certainly stabilized," Guilfoyle said, highlighting that since OPEC been talking about a deal the price of oil has stayed around $40 beginning in late February. 

The U.S. Dollar Index, which is a measure of the dollar relative to six foreign currencies, rose 0.06% to 101.46. The index had been lower for most of early Monday.

Cyber Monday, the Monday after Thanksgiving, is traditionally the busiest online shopping day of the year. But with stores releasing Internet deals earlier, more and more shoppers decided to skip the mayhem at brick-and-mortar locations and purchased goods online. A National Retail Federation survey estimated that more than 122 million Americans will shop online Monday, a million more than the prior year. 

Consumers spent $3.34 billion shopping online on Friday, a 21.6% increase from the same day last year, according to Adobe Digital Insights.

However, a few retailers, like J.C. Penney (JCP) - Get Report and Target (TGT) - Get Report , saw strong starts to the holiday shopping season at their store locations. Online shopping giant Amazon.com (AMZN) - Get Report will be in focus on Cyber Monday. Amazon shares fell 1.6%.

Schlumberger (SLB) - Get Report , the world's largest oil driller by market value, signed a preliminary deal to study an Iranian oil field, the Journal reported. The stock fell slightly.

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Shares of Lockheed Martin (LMT) - Get Report  dropped 0.2%. Israel's security cabinet approved the purchase of an additional 17 Lockheed F-35 stealth fighter jets, bringing its total number on order to 50, according to reports.

Time Inc. (TIME) shares gained 18% in early trading after its board didn't accept a buyout offer of $18 a share from Edgar Bronfman Jr., according to the New York Post. Bronfman is reported to have worked with Access Industries and Ynon Kreiz, a Israeli businessman, on the bid.

Shares of information technology services company Cognizant Technology Solutions (CTSH) - Get Report  jumped 8.2% after activist investor Elliott Management, which owns 4% of the stock, sent a letter to the company saying it should start paying dividends to shareholders and complete a $2.5 billion share-repurchase plan. Elliott also called for new members on the board of Cognizant.

H&R Block (HRB) - Get Report  fell 5.9% as BTIG downgraded the stock to sell from neutral, noting that President-elect Donald Trump's promise to simplify tax filing may be a negative for the company. 

The economic calendar in the U.S. is quiet Monday but traders will be gearing up for data releases later this week, including the U.S. jobs report for November on Friday and the second estimate of third-quarter GDP on Tuesday.