"Investors can always go to cash if they're looking to avoid taking a big hit. And if you think you can't sustain more than a 10 percent loss with your assets, then you probably shouldn't be in anything where that can happen, namely the stock market," said Magyer. "I think selling now is reasonable if you can't sustain more than a 10 percent loss in the market. ... I understand why some people are concerned, the threat of a downgrade let alone a default is real and the impact will be painful, but I don't think the best play is to go completely conservative. ... I do think that blue chip stocks are the best play over the long-term for patient investors, particularly for retirees. ... The last place I'd want to be right now is a lot of the high-flying IPOs that have been out, so LinkedIn, Pandora, Zillow, each of those are ridiculously priced."
"If you are a small investor, there is absolutely nothing wrong with moving to the sidelines on a short-term basis to wait till the dust settles," said Hugh Johnson, chief economist at Johnson Advisors.
"We believe that market movements should not dictate your investment strategy. If you are nervous about the stock market and are unable to withstand a severe decline, consider selling down to the your sleeping point. In other words, adjust your stock position to a level that enables you to sleep at night, but it should be a modest (not dramatic) adjustment. But to re-emphasize, most investors should stay the course," said Vanguard.
ABC News' Dan Arnall and Jim Avila contributed to this report.