Wall Street had its wildest week in years

America's economy remains strong -- for now -- but it's hard to tell just how the shock might affect global supply chains, trade and ultimately economic growth.

Perhaps the most important question is one without an answer: how long will the outbreak last? Worldwide cases have surpassed 100,000 and spread to nearly 90 countries.

Amidst the onslaught of headlines on the virus this week US stocks traded so erratically that they gave investors whiplash.

The Dow started the week with the best one-day point gain in its history -- 1,294 points -- as the market rebounded from losses in the prior week that were the worst since the 2008 financial crisis. That uptick didn't last long. On Tuesday, the benchmark tumbled nearly 800 points, then rallied rallied nearly 1,200 points Wednesday. Stocks dropped again on Thursday and Friday, but ultimately finished the week higher.

The Dow, S&P 500 and Nasdaq Composite all bounced in and out of correction territory -- defined as 10% below their most recent peak -- throughout the week, ending Friday in correction territory.

The turmoil extended well beyond stocks.

Oil prices collapsed on Friday after major oil producing nations failed to agree on supply cuts.

Oil had already been hammered over worries that demand would drop because of reduced factory activity on the back of the outbreak. The commodity fell into a bear market last month, defined as 20% below its most recent peak. Without supply cuts in place things could get worse.

US oil prices on Friday settled 10.1% lower at $41.28, the biggest one day percentage drop since November 2014. It was the lowest close since August 2016.

The 10-year US Treasury yield dropped below 1% for the first time ever this week. Investors piled into safe haven government bonds, which pushed prices down and yields higher.

Bonds are also an expression of interest rate expectations, and fixed income investments are a traditional hedging tool when stock investments get hammered. All this contributed to the yield move.

And it didn't stop there: the 10-year yield dropped below 0.7% on Friday, a fresh all-time low.

"The big question on every trader's mind is when will yields stabilize," said Edward Moya, senior market analyst at Oanda.

Central bank policy isn't giving yields any reason to be higher, either. The Federal Reserve announced an emergency half-point interest rate cut on Tuesday -- the first of its kind since 2008 -- as central bankers around the world are loosening monetary policy as a way to combat the virus fallout.

Market participants are somewhat divided about the need for the rate cut.

The central bank's action hammered home that the Fed is willing to do whatever it takes to ensure that America's expansion continues. Yet a surprise cut of this magnitude signals that the country might be in more dire straits than initially thought. With little economic data since the virus outbreak has gotten underway, it is hard to tell.

What's different this time is that the issues originated not in the financial markets but in the real economy, said Lee Ferridge, head of macro strategy for North America at State Street. That's why further rate cuts might not help, he maintained.

Still, Ferridge believes the central bank could slash rates as low as zero if cases of coronavirus in the United States continue to increase.

Friday's February jobs report showed another strong month for the US labor market, with new jobs exceeding expectations and the unemployment rate falling back to its historic low of 3.5%. But the survey report was completed before coronavirus worries gripped the United States. Economists worry about a much bleaker picture for March.

Strong economy or not, the market expects more rate cuts at the Fed's regularly scheduled March 18 meeting. The CME's FedWatch Tool shows a 46% chance of a further half-percentage point cut, with the remaining majority expecting a 75 percentage point decrease.