Wall Street sees the former secretary of state as a status quo candidate lending stability to the markets, while Republican candidate Donald Trump's stances on foreign policy, trade and immigration are less certain.
Apple , the largest US company by market capitalization, posted after the bell better-than-expected iPhone sales that however continued a declining trend and shares fell about 2 percent, briefly dragging S&P 500 futures to session lows.
Telecoms were down 2 percent, their biggest percentage decline in five weeks, as Verizon lost 2.5 percent. The company added fewer than expected wireless subscribers in the third quarter and revenue fell short of expectations.
The Dow Jones industrial average rose 40.95 points, or 0.23 percent, to 18,202.89, the S&P 500 gained 4.72 points, or 0.22 percent, to 2,144.32 and the Nasdaq Composite added 2.58 points, or 0.05 percent, to 5,246.41.
The Dow Jones industrial average fell 44.85 points, or 0.25 percent, to 18,099.35, the S&P 500 lost 6.59 points, or 0.31 percent, to 2,132.59 and the Nasdaq Composite dropped 25.69 points, or 0.49 percent, to 5,213.33.
Gains in crude prices gave support to the idea that the economy is strengthening, as did a report that showed the number of Americans filing for unemployment benefits fell unexpectedly last week to a near 43-year low.
The Dow Jones industrial average closed about 30 points lower, erasing earlier gains, with IBM contributing the most losses. At session highs, the Dow had risen 96.73 points. The S&P 500 fell less than 0.1 percent, as energy dropped more than 1 percent.
A disappointing forecast from Sprouts Farmers Market weighed on grocers. Sprouts shares were down 13.7 percent at USD 19.68, while Whole Foods shares fell 5.3 percent to USD 29.08 and Kroger shares dropped 4.1 percent to USD 31.32.
The S&P financial index, which tends to rise with expectations for higher rates, slipped 0.2 percent, while the S&P utilities index, which tends to benefit from a lower rate environment, rose 1.1 percent.
"The most important part and what drives our [view on] the EM performance over the long term is the fundamentals, but you need to be aware of the sentiment around EM. Now both of them have aligned," said Gerardo Rodriguez, portfolio manager of the BlackRock Total Emerging Markets Fund.
Nilesh Shah of Kotak AMC says China events create an opportunity for India if marketed well. "We need to demonstrate to the world that we have grown companies like Maruti, which have grown beyond its parent here."