Reuters / Brendan McDermid

Stocks nosedived and oil slumped to a 17-year low Wednesday as government measures failed to dispel coronavirus fears.

The sell-off came after Treasury Secretary Steven Mnuchin was said to have privately warned lawmakers that US unemployment could surge to 20% if the Federal Reserve and Congress didn't take sufficient action.

The Trump administration is seeking a stimulus package worth more than $1 trillion and wants to give upward of $1,000 to every American adult.

"It is not a question of if, but a matter of how bad and how long the coronavirus-induced recession will be," one analyst said.

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Stocks plunged and oil plummeted to a 17-year low Wednesday as investors seemed to brush off sweeping government proposals and actions meant to ease the novel coronavirus' effects on the global economy.

The Dow Jones Industrial Average, the S&P 500, and the Nasdaq tumbled more than 4% as investors braced for a brutal downturn. Oil prices — already hit hard by concerns that the coronavirus would erode demand and by the breakout of a price war between producers — slumped to 2003 levels.

The commodity is "haunted from all angles," Naeem Aslam, the chief market analyst at AvaTrade, said in a morning note.

"The wrecked demand, excess supply, and the ongoing supply war between Saudi Arabia and Russia is adding more trouble for traders," he added.

The broad-based sell-off comes a day after Treasury Secretary Steven Mnuchin was said to have privately warned lawmakers that US unemployment could surge to 20% if the Federal Reserve failed to provide economic support and Congress didn't pass what has most recently been touted as a $1 trillion stimulus package.

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The Trump administration has also signaled its support for giving upward of $1,000 to every American adult, potentially starting in two weeks. It has already deferred tax payments for individuals and corporations and continues to discuss providing aid to small businesses and hard-hit industries such as airlines.

European countries are also taking action. The UK Treasury will guarantee £330 billion, or $397 billion, of bank loans to keep British businesses afloat, while the French and Spanish governments unveiled stimulus packages of 45 billion euros, or $50 billion, and 200 billion euros respectively, Reuters reported.

The novel coronavirus — which causes a disease called COVID-19 — is confirmed to have infected nearly 200,000 people, killed almost 8,000, and spread to upward of 145 countries. In the US, there are more than 6,000 known cases across all 50 states, and more than 100 people have died. The pandemic has disrupted international supply chains, forced business to cut back or close, and hammered consumer demand as people stay home, fanning fears of a global slowdown.

Wednesday's sell-off underlined investors' lingering concerns.

"The fact that markets keep shrugging off the stimulus measures reflects the deep uncertainty about the economic damage about to be done," Neil Wilson, the chief market analyst for Markets.com, said in a morning note.

"We're heading for recession," he added.

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Other analysts reached the same conclusion and warned the fallout could surpass that of the financial crisis.

"It is not a question of if, but a matter of how bad and how long the coronavirus-induced recession will be," Ipek Ozkardeskaya, a senior analyst at Swissquote Bank, said in a morning note.

"The global demand shock will certainly be harder than the post-2008 period, as this time, planes are grounded, shops, restaurants, cinemas, theaters and all public places are closed for weeks," she continued.

"All layers of population are hit financially, physically, and psychologically," she added.

Here's the market roundup as of 4:37 p.m. ET:

US equities plunged, with the Dow Jones Industrial Average down 6.3%, the S&P 500 down 5.2%, and the Nasdaq down 4.7%

down 6.3%, the down 5.2%, and the down 4.7% European equities fell, with Germany's DAX down 5.5%, Britain's FTSE 100 down 4.1%, and the Euro Stoxx 50 down 6.2%.

down 5.5%, Britain's down 4.1%, and the down 6.2%. Asian indexes dropped, with China's Shanghai Composite down 1.8%, Hong Kong's Hang Seng down 4.2%, South Korea's KOSPI down 4.9%, and Japan's Nikkei down 1.7%.

down 1.8%, Hong Kong's down 4.2%, South Korea's down 4.9%, and Japan's down 1.7%. Oil prices tumbled, with West Texas Intermediate down 16.3% at $22.90 a barrel and Brent crude down 8.6% at $26.20.

down 16.3% at $22.90 a barrel and crude down 8.6% at $26.20. The benchmark 10-year Treasury yield rose to 1.18%.

yield rose to 1.18%. Gold slid 2.4% to $1,489.

slid 2.4% to $1,489. Bitcoin slid about 2% to around $5,400.

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