Investors appeared to have turned cautious after the Russian ambassador to Turkey was shot dead in an attack at an art gallery in Ankara.
Defensive sectors such as the S&P real estate sector led the gainers with a 1.09 percent rise, while the telecommunications sector was up 0.73 percent.
“With the backdrop of where it happened, it is a strong enough and a powerful enough headline to have the market pause and see what the broader implications may be,” said Quincy Krosby, strategist at Prudential Financial in Newark, New Jersey.
U.S. stocks have been on a tear since the Nov. 8 presidential election, with the S&P rising 5.7 percent on bets that President-elect Donald Trump’s expected deregulation and infrastructure spending will boost the economy.
The Dow posted its sixth straight week of gains on Friday, its longest streak in a year. The blue-chip index remains less than 1 percent away from 20,000, a level it has never breached.
However, there are some concerns that the rally may run out of steam as policy will take time to be implemented and will likely change as it makes its way through Congress.
“The market is fairly valued right now, but, more importantly, we need to see that earnings acceleration next year. If we do not see that in 2017, then you could see a pullback,” said Matt Jones, U.S. head of equity strategy at J.P. Morgan Private Bank in New York.
Yellen will speak on the job market at 1:30 p.m. ET (1830 GMT) at the University of Baltimore. Her speech comes less than a week after the central bank raised interest rates only for the second time since the financial crisis.
At 12:46 p.m. ET, the Dow Jones industrial average was up 35.21 points, or 0.18 percent, at 19,878.62.
The S&P 500 was up 5.62 points, or 0.24 percent, at 2,263.69.
The Nasdaq Composite was up 33.21 points, or 0.61 percent, at 5,470.37.
The S&P technology index was up 0.80 percent.
Microsoft, Amazon.com and Apple were up between 1 and 2.1 percent, providing the biggest boost to the Nasdaq and the S&P 500.
United Technologies rose 1.7 percent, helping lift the Dow, after Credit Suisse upgraded the stock to “outperform” and increased its price target.
Walt Disney was up 1.8 percent at $105.76 after Bank of America Merrill Lynch added the stock to its U.S. 1 list and said the company’s shares were well positioned to outperform.
Advancing issues outnumbered decliners on the NYSE by 1,873 to 1,037. On the Nasdaq, 1,723 issues rose and 1,057 fell.
The S&P 500 index showed 10 new 52-week highs and no new lows, while the Nasdaq recorded 100 new highs and 25 new lows.