Mohamed El-Erian convinced some in an audience of financial professionals at the Inside ETFs conference on Monday that the U.S. market is not in a bubble.

High returns should continue in 2018, although it will be a bumpier ride than last year, said El-Erian, chief economic advisor at Allianz SE and former president of President Obama’s Global Development Council.

“Gains in valuations are increasingly better supported by the underlying fundamentals,” El-Erian said. “But advisors looking at long-term investments are going to have to look for an edge” to beat out the competition.

If the U.S. can maintain pro-growth economic policies, it will validate the asset prices that are being set now, he said.

The major risks that will have to be faced in 2018 are geopolitical, including North Korea’s weapons buildup and tension in the Middle East, particularly between Iran and Saudi Arabia, he said.

The U.S. is moving toward normalization of its monetary policy, including raising interest rates to a more normal level. What happens if all four of the major world banks in the United States, the European Union, China and Japan move toward normalization at the same time? “We don’t know,”  El-Erian said.

El-Erian said he has reservations about U.S. investors, who have been promised more liquidity than some investments can provide. And investors may be getting too complacent, he said, adding that they are not going to be able to handle normal market dips.

“The good news [about the economy] is that we have reason to be optimistic that the underlying fundamental structures will rise to reach asset valuations” so there will be no bubble, he said.

”What if I had told you a year ago that global equities would reach 22 percent, and U.S. equities would do even better, that the S&P would be positive every single month, and the year would have the lowest volatility? You would not have believed me. But that is what happened,” he said.

“Now, every important component of global growth is picking up at the same time. The growth is real and it is multidimensional,” he said. “Every country except the United Kingdom revised its growth projections for this year upward.”

The U.S. economy saw 3.2 percent growth in 2016, 3.6 percent in 2017 and is projecting 3.9 percent for this year.

“You can argue about the distribution of the money from tax reform, but at least for the short term tax reform will boost the economy,” he predicted.

But “you are right to be concerned about the debt,” El-Erian added. The debt has to be measured in relation to the nation’s income. The real question is, “How much debt can you afford?'”

El-Erian took a poll of the audience at the beginning of his talk and found that 67 percent of the audience of financial professionals thought the United States market is not in a bubble and 33 percent thought it is.

By the end, 74 percent of the audience thought there was no bubble.