"Nearly 90% of S&P 500 Stocks Oversold"

This stuff is not exact, for example choosing one standard deviation as the oversold level is as much art as science. That said, combined with the "We're all going to die headlines" it's time to nibble. DJIA down 201 at 9865.
From Bespoke Investment Group:

As of earlier today, 449 (89.80%) stocks in the S&P 500 were trading at least one standard deviation below their 50-day moving averages. There haven't been this many oversold stocks in the S&P 500 since the depths of the Financial Crisis in 2008. The question investors have to ask themselves now is whether the current situation is bad enough to warrant the across the board selling that we have seen over the last several days.