Investors remained cautious following comments a day earlier from Federal Reserve Chair Janet Yellen, who suggested that stock prices might be too high.
The Dow Jones industrial average rose 68 points, or 0.4 per cent, to 17,910 as of 11:45 a.m. Eastern time Thursday. The index is coming off of two days of losses and is barely positive for the year.
The Standard & Poor's 500 gained six points, or 0.3 per cent, to 2,086. The Nasdaq composite increased 21 points, or 0.4 per cent, to 4,940.
Whole Foods Market slumped 10 per cent after its sales fell short of analysts' estimates.
Bond prices rose. The yield on the 10-year Treasury note fell to 2.21 per cent.