"Longer term we’re looking at a market that is a bear market," Carter told "Squawk Box Europe."

While we can expect a rally over the next three to five weeks, this is a downward spiral that is not going away any time soon, he said.

"A trend is a trend until it ends, and we’re actually looking for the Dow to take out 10,000 by the end of the year," he added.

There are too few sectors holding the markets up, and too many dragging it down, to consider getting back into non-recession-proof sectors, according to Carter.

"A large percentage [of sectors], like financials, are getting hammered. A lot of the darlings of the past are going to get taken out back and get shot," he said.

"I think we have to recognize the recessionary forces that are bringing to bear," Hendry told CNBC. "Don't fight that, just go with the flow of the relative momentum."

Hendry said the outlook is particularly bleak for financial and technology stocks -- the two largest components of the S&P 500 -- which he said have both seen a bubble.

"When a sector becomes infected by a bubble…what history reveals is it takes 25 years to regain the highs that we saw in real terms," he said.

When it comes to fighting a U.S. downturn, now is the time to relocate assets into gold and oil, preferably through an ETF tied to the direct price of the commodity, Carter said.

He also said investors should be looking to buy into over-achievers.

"The nice thing is when you get a really down market like this the stars shine out … and when the overall market turns around, that's where you’re going to put your money," Carter said.

“I would much rather buy stocks that are near their highs in an environment like this than try to bottom-fish."

Hendry took the view that in a sustained market downturn, successful investing requires looking for more unconventional assets such as agriculture that have the potential to outperform the market.

"I think the most important thing to know is you don’t have to short this market," Hendry said.

"If you want to stay involved the most important thing is make sure the stock you own is trending higher vis-à-vis the marketplace."