The Dow Jones industrial average edged up 0.08 per cent to end at 16,790.19 points.
The S&P 500 lost 0.36 per cent to 1,979.92 and the Nasdaq Composite dropped 0.69 per cent to finish the day at 4,748.36.
A surge in DuPont’s stock helped to keep the Dow Jones industrial average in positive territory, but the S&P 500 and Nasdaq lost ground, with a sharp drop in biotech stocks.
The S&P health index lost 2.33 per cent, the worst performer among the ten major S&P sectors. The sector has been under intense scrutiny over high drug prices.
The Nasdaq biotechnology index ended down 3.77 per cent, recovering from deeper losses of around 6.6 per cent. The S&P 500 index had gained 5.6 per cent over the previous five days, after a weak US jobs report hinted at economic weakness, but also lowered expectations the Fed will raise interest rates this year.
DuPont rose 7.67 per cent after chief executive Ellen Kullman said she would step down. Pfizer and Merck were down 2.06 per cent and 2.79 per cent, respectively, both the biggest drags on the S&P health index.
PepsiCo rose 1.31 per cent after it reported better-than-expected quarterly results and raised its forecast for the year.
After the bell, shares of Yum! Brands dropped 16 per cent. The restaurant operator reported third-quarter results, including trouble in its key China operation, that disappointed investors.