Stocks were UP (at exuberantly) with year-end Santa-Clause Rally for a longer time expecting trade deal to come which was signed Jan 15th.
Market makers were waiting for some opportunity to correct either 3% or 10% (which I do not know at this stage) and they need a scapegoat which will be Coronavirus.
Stocks work sinusoidal ways, UPs and Downs, market makers must bring down suddenly (or slowly) without a hint to retail investors. Suddenly will normally happen within 3 days, slowly may happen within a month.
At this stage, all stocks, including AAPL is priced in with refinitiv consensus estimate, but they do not know what is the future growth rates. This will only be known during results time and prices will react based on future growth potential.
Since US economy is strong with indirect QE (FED pumping REPO $100 billion/month) is effective, we do not foresee any big fall until election results. Trump has the lucky star to continue the stock growth !
Market makers (Mainly WS/big banks/funds) must bring down so that they gain and retail investors lose money. It is a typical gambling happens in stock market. We see this twice (easily) or thrice in a year.
Remember Ray Dalio hedge against market fall so that he protects hedge fund net worth !
BTW: I do not know what will happen tomorrow !
I may be right or wrong, viewers must do their own analysis.