U.S. markets and stock exchange traded funds weakened Tuesday after a mixed start to the earnings season and a hiccup in Johnson & Johnson’s coronavirus vaccine trials.

On Tuesday, the Invesco QQQ Trust (NASDAQ: QQQ) rose 0.1%, SPDR Dow Jones Industrial Average ETF (NYSEArca: DIA) was down 0.4% and iShares Core S&P 500 ETF (NYSEArca: IVV) fell 0.5%.

Weighing on the notion of a quick Covid-19 vaccine, Johnson & Johnson said it would take “a few days” to review its halted clinical trial after an unexplained illness in a study participant, Reuters reports.

The J&J news is “an excruciating reminder of the difficulties that the coronavirus has brought on the economy,” Eric Schiffer, chief executive officer of private equity firm Patriarch Organization, told Reuters.

“It’s a reminder that while we have this race to get a vaccine, it could actually take longer,” Paul Jackson, global head of asset-allocation research at Invesco, told the WSJ. “If we get one through the trials and authorized, that would be a great step, but then it will still take quite some time to get it widely distributed.”

Further adding to the negative outlook, U.S. House Speaker Nancy Pelosi rejected President Donald Trump’s latest stimulus package idea in the latest sign that a deal on Covid-19 relief remains uncertain ahead of the presidential election.

The cloudy outlook could pressure investors as the third quarter earnings season begins.

“Earnings season will create a lot of volatility, especially ahead of the election,” Ludovic Subran, chief economist at Allianz, told the Wall Street Journal.

Airline stocks weakened after Delta Air Lines posted a steep decline in sales for the third quarter and warned that Covid-19 will continue to deter traveling demand for years.

Meanwhile, financial stock also slipped following a string of earnings reports from JPMorgan Chase and Citigroup.

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