While stocks ended close to where they began, their prices were volatile throughout the day. Stocks opened slightly higher but soon fell after Russian media reported that naval ships were en route to Syria, raising worries of a wider conflict and sending the Dow Jones industrial average down as much 148 points in the first half-hour of trading. The Dow rose as high as 15,009 and dropped as low as 14,789 — a big 220 point range.
"Clearly, (Russia) made the market nervous," said Dean Junkans, chief investment officer for Wells Fargo Private Bank, which has $170 billion in assets under management.
The Standard & Poor's 500 index rose less than a point, or 0.01 percent, to close at 1,655.17. The Dow ended down 14.98 points, or 0.1 percent, at 14,922.50. The Nasdaq composite rose 1.23 points, or 0.03 percent, to 3,660.01.
Traders were rattled by conflicting forces. A mediocre August jobs report suggested that U.S. economic growth was slowing, while providing a reason for the Fed to keep up its stimulus program. The geopolitical risks of Syria added to the uncertainty Friday.
One clear trend emerged: investors moved money into safer assets. The yield on the 10-year Treasury note fell to 2.94 percent from 3 percent the day before. Relatively safe, dividend-paying stocks such as utilities were among the best performers in the S&P 500 and gold rose more than 1 percent.
Wall Street was unnerved by signs that the confrontation between the U.S. and Syria over Syria's alleged use of chemical weapons on civilians was getting worse. Three Russian naval ships sailed toward Syria on Friday and a fourth was on its way, the Interfax news agency reported, a sign that Russia may assist Syria in case the U.S. does strike. However, Russia President Vladimir Putin's chief of staff said the ships were intended to help evacuate Russian citizens if military strikes become necessary.
"These are troubling developments," said David Chalupnik, head of equities for Nuveen Asset Management. "Syria is turning into something bigger that what it started out to be."
The price of crude oil rose as traders anticipated that any escalation of tensions in the Middle East might disrupt the flow of oil from the region. Oil rose $2.07 to $110.43 a barrel.
Putting aside Friday's volatility, Wall Street had a pretty good week. The S&P 500 rose 1.4 percent for the week, and the Nasdaq was up nearly 2 percent. It was the best five-day gain for the S&P 500 in two months.
U.S. employers added 169,000 jobs last month, fewer than the 177,000 economists had forecast. The number of jobs added in July was estimated by the government at 104,000, down from an earlier 162,000.
"This was a horrible set of jobs figures, starting with large revision to last month's number," Tom di Galoma, head of fixed-income rates sales at ED&F Man Capital, wrote in an email to clients.
Friday's jobs survey is the last major piece of economic data the Fed will have to consider before its September 17-18 policy meeting, when it will decide the fate of its large bond-buying program.
The Fed has been buying $85 billion in Treasurys and other bonds each month to keep interest rates low and encourage hiring and economic growth. It was widely believed that the Fed would start phasing out its purchases this month.
Most market watchers said they still believe the Fed will start pulling back in September, however the amount of the pullback may be smaller, Nuveen's Chalupnik said.
Stocks making big moves included:
— Mattress Firm, which plunged $6.10, or 15 percent, to $35.59 after the company reported a second-quarter profit that fell far below financial analysts' expectations.
— VeriFone Systems jumped $2.09, or 10 percent, to $22.81 after the electronic payment terminal maker reported third-quarter results on Thursday that beat Wall Street expectations.