If you do not need to sell, don't.
The markets are tanking more than is necessary for even the most severe recession. What makes it scary is that it is happening in days, not months, relentless-- it's happening in internet time.
The S&P500 goes to 800 and Dow to 7500, these are inevitabilities. But you can't trade it because the volatility is too high-- so don't.
Some people need to sell-- especially hedge funds caught the wrong way; or people selling the good stocks to raise money to cover debts, taxes, redemptions, whatever.
If you have cash and can wait for 800 and 7500, then feel free to buy then. Stocks aren't falling, they are being stomped on, compressed. When the real companies rebound, their stocks will likely explode higher, like.. a coiled spring.
Let me quote the late, great, Mitch Hedberg: "I'm tired of following my dreams. I'm just going to figure out where they're going, and hook up with them later."
Don't follow the market. Just meet it at 800.