U.S. stock markets suffered their steepest Christmas Eve decline in decades Monday, defying the best efforts by the Trump administration to instill confidence, and coming very close to ending a record 10-year upward run.

By the end of Monday’s shortened holiday trading session, the great bull market that began in the lows of March 2009 lay lifeless, capping a three-week, 16 percent sell-off of the S&P 500.

President Trump and administration officials faced intense scrutiny of their unorthodox attempts to steady nervous markets. Treasury Secretary Steven Mnuchin’s phone calls Sunday to major U.S. banks further stoked anxiety among traders, while Trump’s Monday tweet attacking the Federal Reserve for not having “a feel for the Market” appeared to exacerbate the day’s sell-off.

Investors have been shaken by recent economic and political ­developments, including the abrupt resignation of Defense Secretary Jim Mattis; a partial federal government shutdown; an interest rate hike by the Federal Reserve; speculation that Trump might seek to fire Fed chief Jerome H. Powell; Mnuchin’s unusual calls to U.S. banks; and Trump’s sudden decision to withdraw U.S. troops from Syria against the counsel of his national security team.

For investors, an ugly three months after 10 very good years

Democratic leaders attributed the stock market declines to Trump.

“It’s Christmas Eve and President Trump is plunging the country into chaos. The stock market is tanking and the president is waging a personal war on the Federal Reserve — after he just fired the Secretary of Defense,” House Minority Leader Nancy Pelosi (Calif.) and Senate Minority Leader Charles E. Schumer (N.Y.) said in a joint statement shortly after markets closed Monday.

Amid the flurry of events, Mnuchin and acting White House chief of staff Mick Mulvaney had sought to calm investors Sunday by insisting that the fundamentals of the economy remain strong.

But their efforts were unsuccessful, as market nervousness was on full display Monday. The Dow Jones industrial average smashed its century-old record for a Christmas Eve percentage drop, falling 653 points, or just under 3 percent.

“I can’t tell you the last time a percentage fall came in that short a time,” said Scott Wren, global equity strategist at the Wells Fargo Investment Institute. “Just three weeks ago, we were still looking at a successful 2018. Stocks then fell off a cliff.”

The slide spread to Asia on Tuesday morning, with Japan’s Nikkei 225-stock index down more than 5 percent at midday and Shanghai’s main share index down nearly 2.5 percent by 11 a.m. The dollar hit a four-month low against the yen of 110.05 in Tokyo, extending a seven-day losing streak. Traders and experts there talked of a “Black Christmas” and the “Powell shock.”

December is usually a healthy month for stocks, but this month has been the worst since 1931.

The tech-heavy Nasdaq Composite that was key to the bull market declined 140 points Monday, about 2.2 percent on the day, to sink deeper into bear territory. A bear market is 20 percent off recent highs.

The Standard & Poor’s 500-stock index was down 65 points, or 2.71 percent, to close at 2,351. All 11 sectors of the S&P were down and are negative for 2018.

Investors are still grasping onto hopes of a last-minute recovery. Since 1950, stocks have rallied 1.3 percent on average during the last five days of the year and the first two days of the new year.

As blue chips sank even deeper into the red, Trump inserted himself into the conversation. Ensconced at the White House and, in his own telling, “all alone” on Christmas Eve, Trump took to Twitter to assign sole blame for the sell-off to the Federal Reserve. He likened the central bank to a golfer who “can’t putt.”

“The only problem our economy has is the Fed,” the president said in a tweet. “They don’t have a feel for the Market, they don’t understand necessary Trade Wars or Strong Dollars or even Democrat Shutdowns over Borders. The Fed is like a powerful golfer who can’t score because he has no touch — he can’t putt!”

The treasury secretary earlier staged an unusual intervention in the markets, shaking financial analysts, bankers and economists Sunday when he announced that he had called the leaders of the nation’s six largest banks to re­affirm that they had ample credit to extend to American businesses and households.

Mnuchin’s statement caused alarm because there had been no prior doubt as to the liquidity and lending abilities of the banks.

“He raised the specter of concern in one of the most solid areas of the U.S. financial system — the solvency of the banks,” D.C. investor Michael Farr said. “The banks are as solvent as they have ever been. He went to the heart of the economy’s strength and created doubt.”

Mnuchin’s outreach was not widely coordinated throughout the administration, according to people briefed on the discussions who spoke on the condition of anonymity to discuss internal deliberations. The initial Sunday phone calls did not strike some administration officials as unusual, but the readout Mnuchin provided in a news release, which he also posted on Twitter, caught many by surprise.

A Treasury Department official defended Mnuchin’s actions by saying his calls to bank executives were routine confirmations of the strength of the economy during a turbulent time and that his public statement about them was merely a move to be transparent.

Mnuchin and other senior administration officials had been discussing for days how to try to calm investors without coming across as desperate or preachy. But they have struggled to find the right balance.

Mnuchin, who is vacationing with his family in Cabo San Lucas, Mexico, on Monday held a conference call with a presidential working group called the “Plunge Protection Team,” which was created after the 1987 stock market crash to help stem steep drops in the market.

Members of the committee include the heads of the Federal Reserve, the U.S. Securities and Exchange Commission, and the Commodity Futures Trading Commission.

Ed Yardeni, president of Yardeni Research, said the current pullback is a reaction to the Federal Reserve moving too far, too fast to raise interest rates.

“It’s not only the stock market,” Yardeni said. “We are seeing stress in the credit markets and the commodity markets, signaling that the Fed might have been naive in believing after several years of abnormally easy monetary policy, that they could reverse or normalize policy in just a few years. The markets want the Fed to normalize at a much slower pace.”

Trump has long claimed personal credit for market gains and sees a strong economy as central to his reelection hopes in 2020. The president has obsessively monitored recent gyrations, and aides say he has grown furious about the declines of the past week and fearful of a recession.

‘Very possible’ shutdown could last into new year, White House budget director Mulvaney says

Trump has singled out Powell for blame, insisting that the bank’s interest rate hikes are responsible for the downturn.

In a Nov. 27 interview with The Washington Post, Trump said: “I’m not happy with the Fed. So far, I’m not even a little bit happy with my selection of Jay. Not even a little bit.”

Trump suggested that he had a better feel for the markets than Powell, even though the Fed chairman has spent decades in investment banking and at the Treasury Department, and Trump, as a real estate developer, ran a number of companies that went bankrupt.

“I have a gut, and my gut tells me more sometimes than anybody else’s brain can ever tell me,” Trump said in the interview.

The economy and financial markets — stocks, bonds, commodities — are made up of a constellation of factors that are not synchronized. The current stock market pullback may have nothing to do with U.S. banks. The U.S. economy’s fundamentals are sound, even though the stock market is verging on bearish territory.

“The president believes he can tweet himself out of this bear market, and he is just making it worse,” said Jared Bernstein, former economic adviser to Vice President Joe Biden and a frequent Washington Post contributing opinion writer. “History is littered with economies that have been brought down by strongman populists muscling their central banks.”

Damian Paletta and Josh Dawsey contributed to this report.