REUTERS/Lucas Jackson
Traders work on the floor of the New York Stock Exchange shortly after the start of trading August 6, 2014.
The Dow is up 2 points, the S&P 500 is down 1 point, and the Nasdaq is up 4 points.
All eyes the Kansas City Fed's economic symposium in Jackson Hole, Wyoming.
Yellen, who is headlining the proceedings in Jackson Hole, is speaking on the state of the labor market, and said she still sees "significant" underutilization of labor resources.
In addition to Yellen's comments, European Central Bank president Mario Draghi is also expected to speak at 2:30 pm ET.