Wall Street sells off on weak earnings, election fears

Illumina shares plummeted 24.8 percent and were among biggest drags on the S&P 500 after the diagnostic test maker's weak quarterly update. Although overall S&P 500 earnings are currently expected to fall 0.7 percent in the third quarter, according to Thomson Reuters data, a typical number of better-than-expected reports would result in a positive quarter. At the same time, investors are bracing for the U.S. Federal Reserve to raise interest rates by the end of the year.

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Wall Street sells off on weak earnings, election fears