It’s the third down day for Wall Street, led by a decline in tech stocks ahead of that sector’s earnings season.
New York CNN  — 

US stocks took a dive Wednesday as mounting concerns over big tech earnings, rising Treasury yields and political uncertainty drove down all three major indexes.

Investors have been increasingly on edge about the prospect of former President Donald Trump winning the election, a possibility for which Wall Street has been preparing to a greater extent. While polls remain effectively dead-even, Trump’s prospects have grown since the start of this month in political betting markets.

“The logic here is very simple: Candidate Trump has called for a significant increase in import tariffs to revive domestic manufacturing,” Steven Ricchiuto, chief US economist at Mizuho Securities, said in a Wednesday afternoon note. “These tariffs are seen as immediately raising the price of consumer goods and, in the process, reversing the goods deflation that has helped pull inflation back towards the Fed’s 2% target.”

Trump’s policy proposals, if enacted, are also expected to cause the government to borrow significantly more money compared to Vice President Kamala Harris’ policy plans. That would make it riskier to invest in government-issued securities, leading investors to demand higher interest rates to hold US debt.

Treasury yields continued their upward march, with the 10-year note briefly topping 4.25%, its highest level since July. This surge in yields has put additional pressure on stocks.

That rise in bond yields made stock investors nervous. The tech-heavy Nasdaq Composite led the decline, ending the day down by 1.6%; while the S&P 500 and Dow both fell about 1%. For the Dow, this translated to a drop of just over 400 points. At one point early Wednesday, the Dow was down more than 600 points, marking the third consecutive day of losses for US markets. All three indexes settled slightly lower later Wednesday afternoon.

“The equity market is extremely fragile considering the headwinds that are lurking right around the corner,” wrote José Torres, senior economist at Interactive Brokers, in a note Wednesday. “Earnings expectations are buoyant for next year, which increases the importance of forward guidance rather than past results.”

The selloff hit the tech sector particularly hard, with Nvidia dropping 2.8% and Apple falling 2.2% ahead of their earnings reports next week. Investors are closely watching these results to gauge whether large investments in artificial intelligence have led to stronger financial performance.

The Dow was also dragged down by McDonald’s, whose stock was lower by 5.1% Wednesday afternoon. Shares fell as much as 7% after an E. coli outbreak tied to Quarter Pounders in the western part of the United States left one dead and 10 hospitalized. Shares of Dow component Boeing also fell after the aircraft maker reported huge quarterly losses Wednesday and new CEO Kelly Ortberg said “it will take time to return Boeing to its former legacy.”

Investors are also processing mixed signals about the Federal Reserve’s next moves. Recent strong economic data has led traders to question whether the central bank might maintain higher rates for longer than anticipated.

The current market environment suggests continued volatility ahead, said Torres, warning of the potential for further yield curve steepening and increased market turbulence ahead.

CNN’s Elisabeth Buchwald contributed to this story.