"I think a perspective that people should have is to take their eye off the U.S. market and start looking at other areas around the world where things might look a little more fairly valued, perhaps," he said.
Fisher, who oversees $2.7 billion in assets and is ranked among Barron's Top 100 Financial Advisors, said U.S. markets were more fully valued from a price-to-book or a price-to-earnings metric.
"Is it possible that there are risks over there—and our economy is strong here in the U.S.—but is it possible there's also some opportunities that we should be focusing on as opposed to the frothiness of the U.S. market?" he asked.
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Noting that the United States represented about half of capital markets and about 20 percent of worldwide GDP, Fisher said that many investors were less than 50 percent invested in foreign markets.
"I would stay diversified," he said. "Why limit yourself to one yield curve with everything going on with the U.S. government, interest changes, inflation, deflation—everything we're hearing about. I think diversifying across yield curves, across markets, makes good sense."
While risks were certainly higher in developing economies, Fisher argued that the rewards would be greater, as well.
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"If you take the position that risk and return are related, there should be a premium for taking on that risk, and I think investors would be well served long term by having exposure to those areas," he said. "What the actual percentage is is going to be a function of an investor's risk tolerance, but to avoid the emerging markets and to simply be in the U.S. by itself I think would be a mistake."
—By CNBC's Bruno J. Navarro. Follow him on Twitter