I'm not an investment guru either
But the answer depends on how far away from retirement you are. IMO
Your portfolio should already be diversified to help protect against these things, but if you are 15-20 years from retirement, then I'd say to ride it out and consider it an opportunity to buy low again. That's what I'm doing anyway.
Most of my 401k money is spread among a few different index funds that cover large cap, mid cap, small cap, and international. My Roth IRA money is spread in much the same way, but in mutual funds (not index funds) and at different percentages (I have some of this in a REIT also) and I keep some cash in there too just in case I hear about a good opportunity with a specific stock. (for instance as JCP was bouncing around I made about 20% sold, waited until it dropped again, made about another 10% and then sold it for good)
I don't intend on changing much of anything until I'm quite a bit closer to retirement.
An actual financial advisor might have different advice.