October’s history as an irascible month for stocks remained intact in its first two days as markets plunged on fears both real and imagined.

The Dow Jones industrial average gave up all its September gains and then some, plunging nearly 500 points Wednesday to push its losses to more than 800 points for the month. Technology received the biggest shellacking Wednesday, with Intel, Visa, Apple and Cisco running in the deep red.

The pullback’s immediate cause was Tuesday’s dismal manufacturing report, but fears of an economic slowdown, complications over Brexit and never-ending global trade anxiety weighed on investors.

“October’s reputation is preceding itself,” said Sam Stovall of CFRA Research. “Historically, October has witnessed 30 percent higher volatility than the average month.”

The Dow blue chips slumped 494 points, or 1.9 percent, to close at 26,078. Wednesday’s mayhem followed a rocky start Tuesday, which saw a 344-point drop after the Institute for Supply Management’s manufacturing index signaled that September was the worst month for U.S. manufacturing in more than a decade. Tuesday wiped out all of September’s market gains. The Dow’s two-day loss comes to about 3.1 percent. The blue chip 30 is 4.7 percent off its all-time closing high in July 2019.

The Standard & Poor’s 500-stock index and Nasdaq composite index closed down, marking the worst day for stocks since Aug. 23. The broad S&P 500 dropped 53 points, or 1.8 percent, to close at 2,887 on the day. The S&P’s two-day loss comes to 3 percent. All 11 stock market sectors went negative, led by the industrials and the information sector. The S&P 500 is 4.6 percent below its all-time closing high last July.

The tech-heavy Nasdaq gave up 123 points, or 1.5 percent, to close at 7,785. The Nasdaq is more than 6 percent off its all-time closing high in July.

Analysts were finding it difficult to put an exact cause on the sell-off. Some referred to October itself as a jinx month that hosted historic crashes in 1929, 1987, 1997 and during the Great Recession. The month also is known for being a “bottom” for bear markets that have then reversed and turned upward.

Others even speculated that reports about presidential candidate Sen. Bernie Sanders’s health might have sparked the sell-off. Some on Wall Street fear that his Democratic rival Sen. Elizabeth Warren would be unfriendly to Wall Street if she claimed the White House.

“It is all speculation on the source of weakness in the near term,” said Nancy Tengler of Tengler Wealth Management. “Manufacturing was disappointing. Job growth is slowing. In the very short term, the algorithms are reading the headlines and the sell programs are taking over. I am not panicking yet.”

President Trump blamed the volatility on “all of this impeachment nonsense, which is going nowhere.” In a tweet midday Wednesday, he insisted the inquiry was “driving the Stock Market, and your 401K’s down. But that is exactly what the Democrats want to do. They are willing to hurt the Country, with only the 2020 Election in mind!”

Trump’s tweet marked the second time in two days that he has punted the blame for negative economic news. On Tuesday, in the wake of the dismal manufacturing report, he tweeted that Federal Reserve Board Chair “Jay Powell and the Federal Reserve have allowed the Dollar to get so strong, especially relative to ALL other currencies, that our manufacturers are being negatively affected.”

“Fed Rate too high. They are their own worst enemies, they don’t have a clue. Pathetic!” he wrote.

American consumers have been the cornerstone of the economy, but there are concerns that confidence could start to slip. U.S. vehicle sales for Ford Motor Co. declined 4.9 percent during the third quarter, the company said Wednesday, with demand for the top-selling F-series pickup starting to slouch. Its stock had shed 4 percent by midday Wednesday.

The National Retail Federation is set to present its perspective Thursday when it releases its holiday shopping season forecast.

This week’s sell-off is echoing 2018’s fourth-quarter mayhem. Stocks last year hit their high on Oct. 4 before beginning a three-month, 20-percent slide that culminated on Dec. 26.

Washington, D.C., investor Michael Farr warned that that chain of events could be repeated unless calmed minds prevail. “Investors need to be as data-dependent as the Federal Reserve, and these appear to be emotional swings,” he said. “The consumer represents 70 percent of gross domestic product and is still seeing wage gains and continuing to spend. That is positive data, and we need to be careful that we don’t talk ourselves into an unnecessary bear market.”

The impeachment tumult comes as economists grow increasingly concerned about the year-long trade war between the United States and China, and weakening economic guideposts,

“There is no end in sight to this slowdown, the recession risk is real,” said Torsten Slok, chief economist at Deutsche Bank Securities, in an email to clients Tuesday.

Hiring cooled in August, federal data show, but a reportWednesday from ADP and Moody’s Analytics found that the private sector created more jobs than expected in September, even while the pace slowed in the face of a tight labor market.

Companies hired 135,000 more workers in September, according to the jobs report, topping the 125,000 that economists surveyed by the Dow Jones had expected. But the September figure was the slowest since June and brought the 2019 monthly average down to 145,000 — a marked drop from the 214,000 reported in the year-ago period and the 157,000 reported in August.

Tuesday’s manufacturing news erased hopes of a quick turnaround for the industry — which represents 10 percent of the gross domestic product — and bruised Trump’s vows to revive blue-collar jobs. Manufacturing fell into a “technical recession” in the first half of the year, and the latest data suggests that situation is only growing more grave.

The European markets were on a downturn, with the London’s FTSE sliding more 3.2 percent; the German DAX shedding 2.8 percent and the French CAC 40 falling 3.1 percent.

Also on Tuesday, the World Trade Organization downgraded its forecast for global trade growth for this year and next. The U.S.-China trade war and a global economic slowdown spurred economists to project that world merchandise trade volume is expected to rise 1.2 percent in 2019 — markedly slower than the 2.6 percent forecast in April. For 2020, the forecast estimates 2.7 percent growth instead of 3 percent.