The stock rout related to coronavirus fears continued Tuesday with the Dow Jones Industrial Average losing nearly 900 points, adding to Monday's 1,000-point plunge. The S&P 500's two-day loss of 6.3% was the largest for the benchmark since August 2015. A combination of factors spooked investors and caused the Dow to turn negative after starting the session in positive territory, including a decline in the 10-year Treasury yield to a record low and comments from health officials warning of a possible outbreak in the U.S. The Dow dropped 879.44 points, or 3.1%, to 27,081.36 after being up more than 180 points at one point shortly after the open. The benchmark posted back-to-back losses of at least 800 points for the first time ever. The S&P 500 slid 3% to 3,128.21, posting back-to-back declines of 3%. The Nasdaq Composite fell 2.8% to 8,965.61, and turned negative for the year. Monday's session was the market's worst in two years.

All in all, the S&P 500 lost $1.7 trillion in market value in two days, according to S&P Dow Jones Indices. "Volatility is normal," said Art Hogan, chief market strategist at National Securities. "What's scary about this particular drop from the all-time high is it has snuck up on us so quickly in a short period of time." "When you juxtapose that against a mentality of 'we don't know how big this thing can get,' that makes it feel like it's a bottomless reaction in the market," Hogan said. These declines also put the Dow and S&P 500 about 8% below their record highs reached earlier this month. The Nasdaq closed 8.9% below its all-time high from Feb. 19. Technology stocks such Apple and Facebook have fallen into correction territory, down more than 10% from all-time highs hit just last month. "I understand the inclination to buy on the dip. I understand that the path of least resistance in this market is to bounce up ... but I stress, this is different," Mohamed El-Erian, chief economic advisor at Allianz and former Pimco CEO, told CNBC's "Squawk Box."

'This could be bad'

U.S. equities dropped as Centers for Disease Control and Prevention (CDC) officials briefed the U.S. on how to get ready if the coronavirus outbreak worsens domestically. "We are asking the American public to work with us to prepare in the expectation that this could be bad," Dr. Nancy Messonnier, a top official at CDC, told reporters on a conference call. Stocks fell even as top White House economic advisor Larry Kudlow maintained that the coronavirus was contained so far in the U.S. and that economic growth had yet to be significantly affected. Traders were unnerved by the bond market, which pointed to slower economic growth around the world. The 10-year Treasury yield traded at 1.33%, hitting an all-time low. The 30-year U.S. bond yield also reached a record low. Bond prices move inversely to yields. "With global investors chasing after U.S. assets, specifically fixed income, there's significant pressure on rates to stay low," said Andrew Thrasher, founder of Thrasher Analytics. "This doesn't mean we won't see some countertrend moves in the 10-year, but the trend is well defined to the downside right now which is not one I'm overly eager to fight." The drop in yields pushed bank stocks down. Bank of America fell more than 5% while JPMorgan Chase closed 4.5% lower. Citigroup and Wells Fargo declined by 4.3% and 2.7%, respectively. Lower rates could hit bank profit margins.

Spreading outside of China